If he's truly a donkey, I would call. If he's a solid player, you have some thinking to do. Yes, donkeys do call raises out of position with crap like K2, but you probably have the best hand at this point. Against a solid player, you have to consider other things like, what he limped in with, etc. Although, if a solid player limped in UTG with AA or KK, he would've reraised you preflop. Call.