Why do Male strippers wear costumes?

The other day me and some girl freinds decided to be and see a male strip tease show. All the guys wore theese costumes or had a gimmick. One was a dressed like a terrorist, one was a fireman, one was a surgeon, one was dressed as a limo driver and the list goes on and on. When it comes to girls takeing off their clothes (I have seen female s trip shows as well) they just go and strip. They don't spend half the time with alter ego's. Why is that?