A really, really good comeback doesn't just make you laugh - it makes you groan. Hitting someone back with something you just know is going to sting in the morning isn't for the faint of heart. It requires a true savage to shamelessly attack someone's weakness without caring about their feelings.
The trouble with good comebacks is that if you live by the sword, you'll die by the sword. So be careful if you use any of the following as inspiration the next time you're in a back-and-forth roast session with your friends, because they might hit you with something you're not prepared for.