Quote from : Kingsman: The Secret Service Movie

Merlin: Congratulations on completing your first task. Charlie, Roxy, well done. For those of you who are still confused, if you can get a breathing tube through the U-bend of a toilet, you have an unlimited air supply. Simple physics... worth remembering. Eggsy, well done for spotting that was a two-way mirror.
Charlie: He's probably seen enough of them.
Merlin: Yeah, you can all wipe the smirk off your faces because as far as I'm concerned, every single one of you has failed. You all forgot the most important thing: Teamwork.
[Merlin points at the quarters. The candidates get up and see that Amelia has drowned]
Gary 'Eggsy' Unwin: So much for classic army technique.