I got trigger happy on a sigecrafter pull and got a stack of the tank debuff by casting penance at like 2. I was surprised when our RL wasn't mad at me.
darn my penance. I might have to go to the doctor about it.
Our Holy Paladin caused many wipes in ToT by fooling around and casting Holy Prism on a target near the boss without realizing. Then again, I shouldn't judge since I've done the same with Divine Star and Halo.