SNAFU

"Situation Normal, All F****d Up"

Perhaps more commonly, bowdlerized "F" words are used.

While in no way a World of Warcraft specific term, it is certainly one of many fitting terms used to describe why something did not go exactly according to plan, e.g:

— "Why did you wipe at Ragnaros tonight?"

— "Ah, we just had a sons snafu. Tanks allowed them to walked all over our healers. Otherwise it would have been fine."