Here is how i deal with loud-mouthed kids in Left 4 Dead and other rage-rich games: I keep all calm and quiet until there is a break/pause in the game, so I can 100% focus on chat, I put the mic as close to my mouth as i can, or slam the CAPSLOCK on, and go something like this: "YOU PIECE OF WORTHLESS COCKSUCKING-HOMO-my old friendGET CUNT! YOU SHUT THE FUCK UP! YOU DICK LOVIN LITTLE SHIT! YOU SHUT! THE FUCK! UP!"
Works best with mic, since i am 30, and have a very thick russian accent. There are some who pick it up, and start backtalking, but than i usually go full-retard, and just repeat " DIE YOU CUM DRINKING HOMO PIECE OF SHIT CUNT! DIE!" until it sorts itself out somehow.