LoL @ Zehdons #3.... so many of my Dota friends are THAT GUY.
My personal pet peeves, not necessarily things that ag me on from the internet community, but my closer friends who i team with usually:
1) You just wont learn. Why do you insist on starting with boots of speed ON ROOK? Youre still slower than them and now you're down 525 mana +4/sec, and health+regen. I need you to tear down towers, not take slightly longer to get chased down.
2) The guy who just wont think: My buddy constantly buys tier 2 and 3 of the gold upgrade. Despite showing him the math and him knowing how long our average game lasts (Short enough that T2/3 dont provide ANY profit by the time he buys them) he still does it. I ask him to get a cit up and next time i check ive got two useless, expensive, upgrades and still level 1 creep dmg. WHYYYYYYY
3) Feeders. If you get owned more than twice by the same DG in a row, you need to avoid it. Call for help. YOU CANT TAKE HIM. I promise, if he's your level and owns you twice, there is absolutely no way you will touch him when hes two or three levels above you. you arent helping any.