What I like doing is saying things like "Also, Kha insulted your mother :D"
Or...... you can make it worse and cause them to go full on tilt . . .
when the argument gets heated enough I will do the following:
Player A: RAMBLE RAMBLE RAMBLE! Player B: ANGRY RANTING >:( Player A: RACIST INSULT FOLLOWED BY INSULT TO MOTHER! Blue Moon Wolf: Grabs popcorn Player B: INSULT QUESTIONING SEXUALITY AND INTELLIGENCE D:< Blue Moon Wolf: anyone want some popcorn? it's extra salty :p Player C: love that kind, pass some this way XD
this normally defuses the anger enough to get everyone to stop the fighting. After the match everyone just leaves without so much as a word and my job is done :)