This.
Following is the worst I've seen:
DPS warrior heroic leaps to boss while half the group(including both tanks) is outside room, omfg tank y u pull!?
Healers leave in the middle of combat so tanks die and other people get aggro, lol bad tank cant hold aggro!
Hunter misdirects all trash between juggernaut and shamans to tank and feigns while the raid is down to 1 tank 2 healers and 11 dps, omg retard tank thinks he can tank so much.