Mine is only a funny line when taken in context of the story.
In Mercs 2, the UP factions soldiers regularly spout off the same four lines all game.
The one I hear mostly is "UP can kiss my ass, Im just in it for the paycheck"
I was wasting time one day, just screwing around blowing things up, when I thought hey why not destroy the carmona bridge and make life hell for everyone. So after about 5 or 6 artillery strikes a hefty portion finally collapses. As I was standing at the end of the crumbling portion, my roommate chripped up " I wonder if the game is stupid enough to let people keep driving it."
No sooner had he finished saying it then the sound of a car motor flared up behind us and off flew a UP Raven GL and right before it hit the water we heard, "UP can kiss my ass!"
Now everytime I hear them say it I think of that moment. Favourite line in any videogame.