I mute everyone in 0.0001s after joining, so I have no idea what they are saying.

But then you miss out on them whining and cursing when you kill them. I will mute music or really annoying people, but like to leave most unmuted so I can hear their cries. 

This kid sent me possibly the greatest chain of messages last night after a buddy of mine and I beat his team 2 or 3 games in a row

Subj: GOD HATES YOU

STOP CAMPING YOU F*CKING ****** TRYHARD

Subj: KILL SOMEONE ELSE!!!!

LEAVE ME THE F*CK ALONE AND LET ME CAMP FOR MY AC130 IN PEACE!!!!

Subj: STOP KILLING ME!!!

Dude cmon your ruining my already horrible K/D, taking the fun out of this game for me

Subj: YOU SUCK

I'm gonna kill your family so you can feel the same pain and suffering I am from playing you in this game

(LEAVES LOBBY)

(10 min later)

Subj: Sorry

For some reason my 12 year old finds it necessary to start crap with random people for no reason online. This is his father now, letting you know he has been grounded for 2 weeks and wont be allowed to play CoD until he shows he can maturely interact with other people

"your're a f-ing moron, there is no f-ing lag in MW3"

^the worst insult so far for me

Thats pretty damn funny!!!