In a discussion about Robin Williams, who is a known joke thief (source: http://www.kempa.com/2004/04/26/robin-williams-prince-of-thieves/), I was told "who cares, comedians steal from each other all the time, it's a tradition".

While jokes are certainly passed around among the average Joe, surely a professional comedian who spends hours crafting original work would be irritated if someone else stole that work word-for-word, without any credit to who told the jokes originally.

Am I not seeing the side of the argument which makes it "okay" to steal another persons work?