It depends entirely on the situation... if I'm being presented with unusual levels of human stupidity, my usual response is "someone get out on the dumb side of bed this morning."
However, if it's just crap that there's no help for it's "D.N.F.C, S.E.F.P." or "Dilligaf?"
"Do. Not. Fucking. Care. Someone. Else's. Fucking. Problem." and "Do I look like I give a fuck?"
Yes, I realize they're both acronyms, but in my defense, I rarely ever explain them, leaving the recipients feeling dumber than usual.