Harry Hart: Manners maketh man. Do you know what that means? Then let me teach you a lesson.
Harry Hart: There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self.
Harry Hart: Are we going to stand around here all day, or are we going to fight?
Harry Hart: I'm a Catholic whore, currently enjoying congress out of wedlock with my black Jewish boyfriend who works at a military abortion clinic. So hail Satan, and have a lovely afternoon, madam.
Princess Tilde: If you save the world, we can do it in the asshole.
Harry Hart: The suit is the modern gentleman's armour.
Merlin: You are about to embark on the most dangerous job interview in the world.
Harry Hart: Boys, I've had a rather emotional day, so whatever your beef with Eggsy is, and I'm sure it's well founded, I'd appreciate it if you could just leave us in peace.
Big Goon: This whisky is amazing, you will shit.
Answer: It was to test whether the candidates were willing to do whatever it takes to get the job done. If they were willing to shoot the dog they had been caring for, it means they would be willing to make a tough choice in the field to complete a mission.