Whenever I'm doing particularly well in a FPS game with a kill streak, I just start screaming "KILL ME!!! SOMEONE KILL ME!", "IS THERE NO ONE ELSE?!", and/or "ARE YOU NOT ENTERAINED?!" (from the movie Gladiator).
But the best, and most fun, running joke, while a little bit racist but still funny... well it goes like this. There's a story behind it.
See, one of my ex-girlfriends was a young lady of noticeable African descent (she was black). And friend of mine who enjoys the occasional racist joke and also likes to drop insults on me for dating a black girl. We also play X-Box Live together.
So anyways. We'll be playing the game, insulting each other as always just for no reason other than to provide the team we are on with entertainment. Eventually he pulls out the "n---er lover" line and I start calling him a honky shortly before just saying "Dude, you gotta try it... I'm telling you. Its fantastic, like nothing else!" and I begin to involve every other team memeber. Some join his side, others are like "Yeah man! That's what I'm talking about! I love Beyonce!" with me. So we end up having this long, very comedic conversation about the joys of sexual relations with members of other races, and how "Dude, once you go black, you never go back... I'm telling you." in joking while we enjoy the laughter and confusion of our team mates.
Good times.