Why do homosexuals friend me?

I know this sounds stupid. But on my myspace it says for my orientation: Straight. My profile used to be private, now its not, but why is it that homosexuals keep friending me? Please don’t make a stupid immature joke about this.

I asked my friend and he said “gaydar”. What is gaydar? And is that really why they are friending me? And is this happening to anyone else?