It's bizarre though really, it just seems like such a strange thing to say to anyone let alone a stranger and more than a little retrograde too what with it being 2008 now and everything.
Apart from anything else there are only 4 possible outcomes, none of them that great:
1)The guy you've just targetted is gay and doesn't mind your stating of the obvious
2)The guy you've just targetted is gay and calls you up on your homophobia thereby making you look like the cunt that you so clearly are
3)The guy you've just targetted is straight and ignores you
4)The guy that you've just targetted is straight and kicks the fuck out of you.
So, you either get blanked, humiliated or physically assaulted and yet hard of thinking beer boys who buy all of their clothes at River Island still do this.