I'm the V. The Silent Veteran
These are the ones to watch out for. During pre-game chat they'll say very little. After getting a triple kill they'll say nothing. Even after getting Beyond Godlike they still won't gloat or show off the fact. Why don't they speak much? Because they're so good that they're used to owning and also they're too jaded to speak to random people off the internet.
Strategy: Either run or gank.
Preferred Heroes: Any

So much this ppl here :
IX. The 12-Year Old
"ROFL PWNED LMAO!" Yep, these kids have just hit puberty and have raging hormones. They should probably be venting this rage on Counter-Strike but here they are on Dota. During pre-game chat they'll be saying all the stupid goofy stuff. The good thing about kids is they're easy to own due to their slower brains and bad judgement.
Strategy: Do what I do in real life. Ignore little kids. There are more productive ways to spend your time.
Preferred Heroes: Any