The people who have beaten "you mad?" into the ground. I know how this already sounds "hurr durr you sound mad" but it's honestly just sad at this point. I've been playing Tribes Ascend a lot, and in one game I had two people constantly asking each other if they mad. Like, the conversation was literally "u mad? no, are you mad?" for like 10 lines of text. I spammed the Quite command until they just stopped talking.
Then today I had a guy who was playing tech (a class that can set up a stationary turret, used largely for defense) who had been killing me a lot since I was making a lot of attempts at trying to get our flag back from the enemy (we had each others flags and each team went incredibly heavy on defense). This went on for quite a while and eventually this pretty good guy on our team managed to help me wrestle the flag free and finally cap it. We then cap again and win that match, and the guy playing tech asks me for the next few matches if I'm upset.
The saying has lost all meaning now. It was funny for a short while when used right, now people just spam it because they are not very clever.
Oh yeah, and something else unrelated. A while ago I was playing bad company 2 and this guy would charge me with a knife, so I would shoot him to death. He did this several times and would laugh in this awkward passive aggressive way after every failed attempt. Basically the mentality of "if I lose who cares I'm dicking around, and if I win then you're terrible" just makes me rage.