My funniest is back in ICC heroic.
We are working on heroic LK 25. i am tanking the LK while the MT is on the adds.
As we get ready to pull, i try to press my "Z" to bring up my weapon, instead i hit "X" sitting down as the boss aggro.
I get one-shotted by a 100k crit followed by one of the biggest moment of panic i ever saw in a 25-man raid, it was gloriously funny to watch
Since then i have removed those keybinds and use them for other abilities