In the dictionary ぼけ may come out as 呆け or 惚け meaning "sinility" or "forgetful" or something along those lines. I've even heard that it can be used to describe a person with alzheimers. Today I'm bringing you a much more useful definition of the word.
ぼけ means "moron." I know this because my girlfriend said it to me this afternoon in jest (I think). I suppose other useful terms would be along the lines of "idiot," or "stupid," or "airhead" (well maybe not airhead - that's a relic from my middle school years).
As always, in English or in Japanese, using a word with the proper intonation is important in order to convey the correct meaning. You could, quite literally, scream this word in someone's face and find yourself in a very unpleasant situation as a result of all their friends taking exception to such name-calling, or you could say it to a friend and mean it only in a teasing way.
Sarcasm rules no matter where you hail from.
So why are you still reading ぼけ～！