Fifteen year-old Mick Campbell is trying to navigate the trials of teenage life with the help of his best mates Conor and Tommy. Big mouth Tommy is always bragging about his numerous sexual triumphs, but his mates know his outlandish claims are not always to be believed. But when Tommy tells them both a tale of his latest sexual encounter and dishes out a nugget of unusual advice for self-pleasure, Mick starts to question himself. What if everyone is doing it and Mick is the only one not doing it?

Desperate to fit in, Mick decides to give Tommy's advice a go, but he's not prepared for what he discovers when he does - there's a swelling on his left testicle.

On top of this, things seem to be progressing with Racheal, the girl from school who he's secretly fancied for ages. But Mick doesn't even know how to talk to girls. How is he supposed to go on a date with one? And with the bulge in his trousers growing bigger and bigger, it looks like Mick might have to try and deal with his swelling himself, before it gets in the way of his chances.