Have you ever broached the subject of homosexuality and bisexuality with your friends? If you're worried about it, you could discuss the subject from a purely philosophical point of view before revealing yourself to be of that grouping.

Of course, this depends on whether or not you're the type of people to randomly discuss political, philosophical, and ideological viewpoints as a means of everyday conversation. But I'm sure there are ways of edging the subject into focus, though it may take a bit of patience.