I don't care what age you are when playing those games. As long as you are MATURE. When immature people play those games is what ticks me off.
If the kids are mature, that's fine.... But when was the last time you played with a group of kids that didn't whine and throw fits?
For example, this afternoon I was playing Black Ops in a High Roller Gun Game on Nuketown. There was this kid with a mic that would scream, cuss, and eventually start crying when he was killed and lost the game. Then in the post-game lobby where we picked the next map, he started calling us all very, very naughty words (still crying, by the way), and saying stuff like, "You're all too rough with me, it's not fair," and other such nonsense. It's called High Roller for a reason kid, if you can't take the heat, stay out of the boiler room/kitchen.