It's Happy (half) Hour down at the QI local, so pile in with Sandi Toksvig, Alan Davies, Cariad Lloyd, Josh Widdicombe and (appropriately enough) Noel Fielding for the ultimate festive P-themed pub quiz. Find out how to pull a pint that never runs out, how to play pool with a chicken, and how many wings an angel really has (spoiler alert: it's not two).

Themes

- One of the questions will be about a pig. If the panel think the question is pig-related, they throw a toy pig and shout "Pig" to gain bonus points.

- In the studio is a pub piano played by a man named Sam, who provides musical introductions to some of the questions.

Topics

- Sam plays Hark! The Herald Angels Sing. Sandi asks the audience first if they like the tune, and second what the tune was written about. Written by Felix Mendelssohn, the tune was originally written to celebrate the 400th anniversary of the invention of the Gutenberg printing press, and it was originally called the Gutenberg Cantata. The original German title is Festgesang zur Eroffnung der am ersten Tage der vierten Sakularfeier de Erfindung der Buchdruckerkunst, which translates into English as: "A festive song for the opening of the first day of the fourth secular celebration of the invention of the art of printing". Mendelssohn said he didn't mind what lyrics were added to the tune, provided they were not religious. Eight years after Mendelssohn died, the tune was paired with a poem by Charles Wesley, the most famous writer of hymns in the English language (he wrote over 6,000 hymns). However, the current wording of the carol is by Wesley's co-worker George Whitefield, who wrote the words in 1753. (Forfeit: Christmas!)

- Pig bonus: When building the world's first ice rink, the things you need are a rink and some pig fat. When the first ice rinks were made, they did not have the technology to freeze large amounts of water. Thus the ice was made out of pig fat and salt. The first ever artificial ice rink was the Glaciarium in Baker Street Bazaar, Portman Square in 1844. It cost a shilling to get in and another shilling to go on the ice. The first words on the poster advertising it were: "Not-ice!" Paintings of alpine scenery were on the walls, but the rink stank of pig lard. The technology to make artificial ice rinks was not developed until 1876. It was developed by John Gamgee, a vet and inventor who had been trying to find a way to freeze meat so it could be transported to Australia, but who also realised his idea and technology could be used for recreational purposes. Gamgee had a tent off the King's Road which had a live band to entertain the skaters. His rink only lasted two years, but the technology he invented is very similar to the system used in ice rinks today. The only problem was that in the summer the ice used to evaporate, so people skated around in a fog. Josh gets the pig bonus. (Forfeit: Ice)

- Tangent: John Gamgee's brother was J. Sampson Gamgee, who invented a form of surgical dressing where cotton woll is placed between two pieces of absorbent gauze. Sampson Gamgee is most likely where J.R.R. Tolkien got the name of Samwise Gamgee from in Lord of the Rings. Cariad is a big fan of Tolkien and begins to quote passages from the show, leading other panellists to wonder if they fancy Cariad more or less, later deciding on less. Josh auditioned for the part of Bilbo Baggins in The Hobbit. The day before the audition they reduced the maximum height for the role, but Josh is five foot and six-and-a-half inches tall so was able to qualify. He still failed to get the part. Alan also auditioned for a role in the film, and he was told that for the role he would be in make-up for four hours a day in New Zealand. He was happy to go along with that, but failed to get the part. Noel auditioned for the role of Frodo, but he was told: "You're a bit tall. You look more like an elf. Get out."

- XL: Sandi gives the panel some peanuts, and discusses George Washington Carver, an American scientist and botanist who created over 300 uses for peanuts. She then asks the panel to give any example of one of his uses. Uses included cleaning, medicine (the Aztecs turned roasted peanuts into a toothache remedy), chewing gum remover, oiling squeaky hinges, superglue remover, leather cleaner, wiping scratched DVDs, and placing peanut butter at the bottom of an ice cream cone stops the cone from leaking. In 1916, Carver published a book called How to Grow the Peanut and 105 Ways of Preparing it for Human Consumption, which included using peanuts in chilli sauce, shaving cream, glue, caramel, coffee, shampoo and axle grease. Carver was born into slavery in Missouri in the 1860s, became one of the first Africa-Americans to go to university, studied botany, became known for promoting alternative crops to cotton, and is thus credited for saving the entire economy of the southern United States.

- XL Tangent: In 2017, 12 inmates in an Alabama prison used peanut butter to escape. They put peanut butter to alter the number on a door, tricking a new security guard into thinking that an exit was a cell door. The guard opened the door and the prisoners fled. However, 11 of the prisoners were caught in 12 hours, and the last one was caught two days later. The prison issued a statement saying: "Prison doors have now been renumbered so that peanut butter won't have any effect on them."

- XL Tangent: Not only are peanut flowers extremely beautiful, they only bloom for one day a year.

- Sam plays The 12 Days of Christmas, with the audience singing. However, one of the lines in the song performed these days is wrong. In the original song, they mentioned "Four colly birds", which means "blackbirds". The "colly" is like a "collier". Blackbird presence predates calling birds by about a century. (Forfeit: Four calling birds)

- Tangent: When Alan'' children sing The 12 Days of Christmas he gets angry because they wrongly sing "Five golden rings".

- XL Tangent: Other versions of the "four calling birds" refer to them as canary birds, mockingbirds, and a Scottish version of the song features three plovers, a parrot and a baboon.

- You can enjoy unlimited glasses of beer without getting completely pie-eyed by ordering half a size less every time. To demonstrate this, mathematician Katie Steckles comes onto the stage and tells a mathematical joke: infinitely many mathematicians walk into a pub, the first orders a pint, the second a half, the third a quarter, the fourth a eighth and so on. The person behind the bar stops them from talking and gives them two pints, and tells the mathematicians that their problem is that they don't know their limits. Katie demonstrates how the joke works by getting out a pint full of beer, then an empty pint glass, and then eight other glasses containing some beer. The first of these glass contains half a pint, the second a quarter, and so on until the eighth glass which contains 1/256th of a pint. All of those smaller amounts will fit into the pint glass, but will never fill it fully because it is impossible to get to infinity.

- XL Tangent: This infinite glasses of beer question is similar to Zeno's paradox, a problem from 450 BC. There is a story about Achilles being challenged to a race by a tortoise. Achilles can run ten times as fast as the tortoise, and to be sporting he gives the tortoise a 10m head-start. The race stars, and by the time Achilles has run 10m the tortoise has travelled 1m, by the time Achilles has travelled 1m the tortoise has travelled 0.1m and so on, meaning Achilles would never reach the tortoise.

- XL Tangent: When hearing the story Noel gets confused between tortoises and terrapins. Alan says he has seen long-necked terrapins in a zoo, but he cannot understand what evolutionary benefit the long-neck has.

- XL Tangent: You can find beer in the sky, or to be more accurate in space. About 10,000 light years away is a nebula made up of enough ethyl alcohol for 400 trillion trillion pints of beer. That is enough for every person on Earth to drink 300,000 pints every day for a billion years. Annoyingly however, the alcohol is spiked with hydrogen cyanide. It also contains ethyl formate, the chemical compound that gives raspberries their taste, and it reportedly smells like rum.

- XL Tangent: In 2017, a fraternity party called "Tequila Tuesday" was held at a fraternity house called Sigma Alpha Epsilon in Bethesda, Maryland. The people there had drunk so much that the ambient air in the house failed a breathalyser test. Alan used to take his children to a music group that was in the bar of a rugby club, and he says that the ambient air in that bar would have also failed the test.

- Sandi gives out mince pies to the panel and offers them sixpence. Sam plays Sing a Song of Sixpence and Sandi asks how many blackbirds should be baked in a pie. The answer is none, because originally blackbirds were not baked in the pie. There used to be "surprise pies" where the pastry was first cooked, and then live animals were placed inside the pie, and the animals would emerge hen the pie was opened. One chef, Robert May (born 1588), put birds and frogs in the same pie. (Forfeit: Four and twenty)

- XL Tangent: Robert May's other creations included a pastry stag with a pastry arrow in the side that was filled with claret, so the stag bled when the arrow was removed.

- Tangent: Bride pie was the original dish served at English weddings before wedding cake was invented. If a woman had a baby she was given a groaning pie, as "groaning" was the term for childbirth at the time.

- Tangent: The panel offer the mince pies, the beer, the plate the mince pies were served on, and the toy pigs to the audience. Cariad gives someone some peanuts because they were left out. Cariad once worked as a barmaid in a terrible pub were the police drank in one corner and the National Front drank in the other. When Sandi worked as a journalist she drank in a pub that was half journalists and half crooks. Sandi spoke to one of the crooks, named Charlie, and asked how he was because she hadn't seen him in a couple of weeks. Charlie said he had been up the nick for murder one. Sandi asked if he did it, to which Charlie replied: "No, but I owed them one. While I was waiting for the charges to come through, my arse was going like that", and Charlie mined his arsehole opening and closing with his hand.

- XL: Sam plays a rather scary version of Away in a Manger, and Sandi asks what is the worst that can happen to you if people who don't like you invite you to Christmas dinner. The answer is they will murder you. Examples include the Swedish King Birger in 1317, who invited his brothers Duke Eric and Duke Valdemar to Christmas dinner at Nykoping Castle just south of Stockholm, telling them he wanted to smooth over a family rift as the brothers has led a coup against him. During the night, the brothers were ambushed by a team of crossbowmen, they were led to the castle dungeon and the brothers starved to death. In 1175, Norman nobleman William de Braose invited the Welsh chieftains to Abergavenny Castle to celebrate Christmas and make amends, but when the chieftains arrived in the great hall, the gates were locked and they were all killed. The 16th century writer William Camden wrote that Abergavenny Castle has been, "oftner stain'd with the infamy of treachery than any other castle in Wales."

- Sam plays O Christmas Tree, but the audience get the second line wrong. In the original German, the second line is: "Wie true sind deine Blatter", which translates as: "How faithful are your leaves". The tannenbaum is a fir tree, but the song was not originally about Christmas. The evergreen branches represent constancy and faithfulness, because they never change. The song was originally a folk song about a faithless maiden, who is contrasted with a faithful tree. (Forfeit: How lovely are your branches)

- Tangent: Cariad only knows O Christmas Tree in German, because it was taught to her in German GCSE. In French GCSE both Cairad and Josh learned the Birthday Song, which they sing together, although Josh suddenly stops halfway through because he only got Grade D.

- XL Tangent: The tune of "O Christmas Tree" is also the same tune as "The Red Flag".

General Ignorance

- There is no legal drinking up time after last orders in England and Wales. Previously it was 10 minutes, then 20 minutes, but now it's up to the landlord's discretion. In Scotland however, there is a 15-minute drinking up period.

- Tangent: Originally, 24-hour drinking licences were proposed as a joke by the Monster Raving Loony Party, as a way to beat binge drinking. It became law in 2005, and one judge at the time said that this law would breed urban savages. Actually, both alcohol consumption and alcohol-related crime has fallen since the act.

- Tangent: The Black Iris Brewery in Nottinghamshire tried to organise a piss-up in their brewery in 2017, but they failed to get the appropriate licence, so the event was held in a pub down the road instead and was renamed: "A Piss-Up near a Brewery".

- Angels have either four or six wings, depending on what type of angel they are. According to the Bible, seraphim have six wings and cherubim have four. No angel in the Bible is described as having two wings. The seraphim, the highest in the angel hierarchy are describes as: "Each one had six wings. With twain he covered his face and with twain he covered his feet and with twain he did fly." As well as having four wings, the cherubim have four faces: those of man, lion, ox and eagle. (Forfeit: Two)

- Tangent: In Islam, Gabriel is an angel of revelation, but there is a Hadith that says he had 600 wings.

- XL Tangent: Sandi was coming back on a train from Scotland and went past the Angel of the North, which is one of the most visible pieces of art in the world. On average it is seen by one person every second. It is the largest art statue in the world, with a wingspan of 54m, which is longer than a Boeing 747. It can withstand 100mph winds because the foundations go as far below the ground as it does at the top. A miniature version of the statue that was made by creator Antony Gormley to test the statue out, and in 2008 this miniature became the first item to be valued at £1million on "Antiques Roadshow". The statue has been standing in the offices of Gateshead council for 13 years.

- To play an old-fashioned game of pool you need a chicken. It was a medieval French game called: "jeu de la poule", meaning: "game of the hen", and the object of the game was to take it in turns to throw things at a chicken, and the first to hit the chicken won the bird. In the 19th century, a pool room was where you bet on horse-racing, and the word "pool" comes from the kitty of money everybody contributed to. In American pool rooms, billiard tables were installed to keep the punters entertained in-between races. (Forfeit: A cue; A table)

- Tangent: The panel play jeu de la poule, but instead of using a real chicken they bring out chief QI elf James Harkin, dressed in a chicken suit and wearing a harness with two Velcro pads on his chest and back. The panel throw balls at the pads while James tries to avoid them. While this is going on, Sam plays The Birdie Song.

Scores

- Noel Fielding: 7 points
- Cariad Lloyd: -2 points
- Alan Davies: -14 points
- Josh Widdicombe: -25 points