Sandi and Alan are joined by Bill Bailey, Sally Phillips, Daliso Chaponda and a virtual studio audience to look into a series of random questions.

Theme

- This episode was recorded in front of a virtual audience.

Topics

- Sandi asks the panel for something that is truly random. One thing that is not random is the shuffle option on music playlists. People thought that the random function did not shuffle the songs randomly enough. While the system was entirely random, the brain is designed to look for patterns. Thus a truly random playlist may play the same song three times, and people will think that some songs are played more than others. Spotify thus had to change their algorithm to make it appear more random than it really was. The National Lottery however, is random. Thus, to win the most money you should pick the numbers that nobody else would pick, as you are less likely to share the jackpot with someone else. As people often tend to pick numbers involving birthdays, it is best pick numbers over 31. Also, avoid anything featuring the lucky number 7 and don't play last week's numbers. A German study showed that 12,000 people will play last week's numbers.

Tangent: If you put your finger in your ear and scratch, it sounds like the noise you hear in Pac-Man.

- Tangent: Birdsong is random because it is stochastic. Repetitive beats will eventually get on your nerves, but birdsong changes ever so slightly enough for people to find relaxing. Bill says his favourite bird is the great tit, to which Sandi says that she too likes great tits. The great tit imitates the alarm calls of other birds, so when it feeds it makes fake alarm calls to make the other birds fly away, and then the tit continues eating.

- Tangent: Alan says that the laughing from the virtual audience sounds like the laughter is coming from the studio next door. Bill did a show in the West End, and the show in the theatre next door was Les Miserables. During the death scene in Les Mis, Bill deliberately engineered it so during the scene his entire audience sang La Bamba. Bill says it was a highlight for the stage management every night.

- Young people's music is so repetitive because the same people write songs for different artists. A 2012 study of almost 500,000 songs recorded between 1955 and 2010 showed that the most recent songs feature less variety in pitch. Timbral variety peaked in the 1960s and has been declining ever since. Modern songs have become louder, but there is less variation in volume. Also modern songs are sadder in tone. Three of the most commercially successful songs in 2012, Taylor Swift's We Are Never Ever Getting Back Together, Katy Perry's Part Of Me and Maroon 5's Payphone were all written by the Swedish music production company, Paratone. There is also the matter of perception. As people get older, they tend to listen to less new music. By the time you reach 33, you stop listening to new music altogether. Music streaming site Deezer did a survey that showed that 60% of respondents listen to the same songs over and over again.

- Tangent: Daliso says the most repetitive music is Kwaito from South Africa. The whole song has one lyric. One song Daliso remembers just had the repeated lyric "Traffic cop, cop, cop". Kwaito however have lots of instrumentals and the lyrics don't matter.

- XL Tangent: The great tit was used in Bruckner's Fourth Symphony.

- XL Tangent: Alan's favourite band when he was a youngster was The Jam, but he says he can't listen to them now, and that he quite likes new music and that you can get a streaming service of your choice where they will show you a whole playlist.

- Tangent: At Sandi's boarding school they had a gramophone but only one single: Leaving On A Jet Plane by Peter, Paul and Mary.

- XL Tangent: The reminiscence bump is when we tend to remember things from our young adult life disproportionately to other years. Very few people remember anything before the age of five, then we have bump between 10-30 years old, especially the 20s which we remember really clearly, and while we do remember the recent past there is a gap which fades back down to the bump, which may explain why we particularly like music during the bump.

- It is a good thing to put a round thing in a square hole when you are planting a tree. If you plant a tree in a round hole, the roots become used to the recently turned soil, and when they hit the more compacted soil at the edge of the hole they respond by spiralling around the edge. Eventually they will grow into a tight ring which will eventually choke or even kill the tree. Square holes are better because the roots are not good at turning right angles. The roots will thus push through the compacted soil and the three has a better chance of establishing itself.

- Tangent: The Guinness World Record for most trees planted by an individual in 24 hours by hand is 15,170 red pine seedlings, by Ken Chaplin from Saskatoon, Canada. He broke the previous record of 12,380 trees, which had been set by his twin brother, Curt. Ken would have needed to plant a three once every four-and-a-half seconds.

- XL Tangent: One of the first citations of the phrase "a square peg in a round hole" comes from journalist Albany Fonblanque. In 1837, he wrote that Prime Minister Sir Robert Peel was a smooth round peg in a sharp cornered square hole, while his Lord Chancellor Lord Lyndhurst is a rectangular square-cut peg in a smooth round hole. Out of the two, Peel's insult was slightly less insulting.

- Tangent: It is better to be a round peg in a square hole than a square peg in a round hole, because the round peg is a better fit. The round peg will fill in a maximum of 79% of the hole, while the square peg fills only 64%. The most famous example of a square peg being fitted into a round hole was on Apollo 13. An explosion forced the crew into the lunar module, but it was only designed to hold two people for 36 hours, not three people for 96 hours. Also, carbon dioxide was building up and they needed to replace the CO2 scrubbers, which absorbs CO2. However, they only had square scrubbers from the main command module. Thus, they did a bodge involving two pairs of underpants (technically known as "liquid cooling garment bags"), two hoses, two socks, a bungee cord and a lot of duct tape.

- XL Tangent: When the film "Apollo 13" was shown to test audiences, people complained that the ending wasn't realistic enough, despite the story being based on true events.

- Tangent: There are many NASA transcripts about escape astronaut poo and the discussion about it.

- Tangent: Duct tape was originally called duck tape, the name dating from 1899 and coming from the Dutch word "doek", meaning "canvas". When Sally was at boarding school, she would wax her legs with duck tape.

- XL: The best way to test if a watermelon is ripe is to slap it. The watermelon will have a deep sound to it if it is ripe, akin to someone knocking on a door or beating a drum. Mark Twain said that to eat a watermelon was to know what the angels eat.

- XL Tangent: In the USA there is a racial stereotype about black people liking watermelons, which does not exist in any of the places Daliso grew up in. Thus, when Daliso went to North America and people implied this stereotype, Daliso reacted by saying: "It's just a watermelon!" Daliso did not know people were implying an insult. Richard Pryor said that he went to Africa and witnessed black people doing every job, which transformed his view on the world because he had only previously known of the racist culture of the USA at the time.

- XL Tangent: The way to test if an avocado is ripe is to remove the stem. If it comes away easily and it is green underneath then it is ripe, but if it is dark then it is not. While 97% of people squeeze them in shops, this just damages them. If the avocado is not ripe, you can hasten its ripeness by putting it in a paper bag with either a banana or apple for 2-3 days at room temperature. This releases ethylene, a plant hormone.

- XL Tangent: In lockdown, Sandi grew tomatoes from seed. She had her first tomato from her plant, which is taller than her, the morning of the recording and she said it tasted better than any other tomato she had ever grown. Meanwhile, during lockdown Sally's road had a sunflower growing competition, and her 15-year-old sprayed all the seeds the house had with Lynx. They did not grow.

- Male Idiot Theory, a term coined by American cartoonist John McPherson, is the idea that young men are more likely to take needless risks. The No. 1 killer of young men aged between 15-34 is stupidity. They have more emergency department admissions, more sporting injuries and a higher mortality rate due to accidents. One reason given for why this occurs is boys being conditioned to take stupid risks.

- XL Tangent: The Darwin Awards, which are given to people who take themselves out of the gene pool by either killing themselves or making themselves sterile, is dominated by men. Sandi's favourite winner was a terrorist who sent a package containing a bomb by post, but the package was returned to him because for inadequate postage, and the terrorist opened it up, forgetting about the bomb inside it.

- Tangent: The panel talks about the way clothes for boys and girls is designed and marketed. A friend of Sally's revealed to her that in the photographic adverts for one particular sporting brand, all the males were shown engaging in the sport, while all the females were either stretching or posing with a ball.

- XL Tangent: Risk is difficult to quantify. One way you can do it is with balloons. The Balloon Analogue Risk Task (BART) sees people playing a computer game where you are told to fill the balloon as much as you can, and the bigger the balloon the more points you get, but you score zero if your balloon bursts. Sandi wanted to try this test with the panellists with real balloons, but they cannot do it because of the risk of infecting people with coronavirus.

- XL Tangent: If you put ten attractive people on a raft in the Atlantic, they will rebel. Mexican anthropologist Santiago Genoves was interested in the fact that most conflicts between monkeys was about access to ovulating female monkeys, so he wanted to see if a similar thing happened to humans. In 1973, Genoves put together a 12m by 7m raft which had ten attractive people on board, who were to sail from the Canary Islands to Mexico. Advertising internationally, the final line-up included an Alaskan waitress, a French scuba diver, an Israeli doctor and a Japanese photographer. Genoves called his experiment the Peace Project, but the press called it the Sex Raft. The experiment failed because nobody got along. People didn't like Genoves's suggestions of who should have sex, or his orders to carry on sailing despite approaching hurricanes. Eventually, the raft mates mutinied and threw Genoves out of the group.

- XL Tangent: The painting used to illustrate the question is "The Raft of the Medusa" by Theodore Gericault. The Medusa was a French frigate which set sail to Senegal in 1816, but the captain hit a sand bank. There were not enough lifeboats, so they built a raft, but only 15 people survived, not helped by taking casts of wine with them. The raft mates turned to cannibalism during the trip. Gericault was so determined to get his painting right that he spent weeks going to morgues, and he kept a severed head in his studio for about two weeks.

- XL Tangent: The longest that someone has survived out at sea on their own is 438 days. Jose Salvador Alvarenga from El Salvador holds the record for the longest amount of time lost at sea. He went fishing with someone he did not know at all called Ezequiel Cordoba, and their 22ft skiff was blown off course. Cordoba lost hope, refused to eat and died. Alvarenga survived by catching fish and bird; drinking turtle blood, rainwater and his own urine; and finding food on floating pieces of plastic. He finally ended up naked on a beach in the Marshall Islands, about 5,500 miles aware from where he set of from Mexico. Alvarenga now has a phobia of water, and he was sued by Cordoba's family who suspected him of cannibalism, but he passed a polygraph test where he said he did not eat him.

General Ignorance

- Apart from humans, the deadliest mammal in the world is dogs. This is due to the spread of rabies, which kills 25,000 people per year. Among the places where this is a risk is India. (Forfeit: Hippo)

- Tangent: Hippos are the most dangerous animal in Africa. Daliso says that guides at Lake Malawi put the fear of God into tourists. However, in Rwanda the guides warn you about the gorillas. Hippos lactate pink milk. There is a problem with hippos in Colombia. Drug baron Pablo Escobar bought some hippos in the 1980s. After his death, the hippos lived on, mated and procreated. There are now about 80 "cocaine" hippos in Colombia.

- Tangent: Calculating the age of a dog in human years is not as easy as most people think it is. Most people think that one dog year is equal to seven human years, but this is wrong. The calculation depends on the species. For example, for Labradors the human age is equal to 16 times the natural logarithm of the dog's age, plus 31. Sandi did this with her four-and-a-quarter year old dog and calculated that she is 54. Logarithmic growths start very quickly, but the increase quickly flattens out.

- The reason why you should put lots of plants in your flat is make you feel better and it is good at stopping depression. According to a study at Drexel University in Philadelphia showed that if you wanted to purify the air in your home using plants, you would need between 100 and 1,000 plants per square metre. In Japan, there is a practice called "forest bathing" (shinrin-yoku) where people relax by visiting forests. About 80% of Japan's population lives in cities. (Forfeit: For better air quality)

- The liquid you hear when you shake a coconut is coconut water. Coconut milk is made from pulped coconut flesh. (Forfeit: Coconut milk)

- Tangent: It is illegal to send coconuts to Fiji via post. Sally found this out when she appeared on Taskmaster, where she was tasked with getting a coconut as far away as possible. She thus tried and failed to send the coconut to Fiji.

- The panel are given toy nerf guns and are asked to demonstrating firing at random. The original definition was to fire at an angle of 45 degrees upwards so the bullets travel as far as possible. (Forfeit: Firing in all directions)

- Tangent: Alan remembers an old QI fact, which is if you fire a bullet from a gun in one hand and drop a bullet from your other hand at the same time, they will both land on the ground at the same time due to gravity. Bill tries this out with his toy gun and shows that it is true.

- XL Tangent: The word "random" to mean something weird and unexpected first came about in the 1980s. It was used in American college students used it to mean someone who does not belong on their dormitory floor.

Scores (assigned randomly)

- Alan Davies: 150,000 points - same as the weight of a blue whale in kilograms. (Alan's 38th victory)
- Daliso Chaponda: 68 points
- Sally Phillips: 33 points
- Bill Bailey: -1,000,000 points