How do I let my friend know I'm bi without being painfully obvious?

I really like her a lot and I am pretty sure she likes me too..We always flirt, stuff like that, but I think she thinks I'm straight. My other friend hangs out with us and always talks about guys and I try not to involve myself in the conversation so that my friend that I like might think I'm not that into guys...lol I dunno...I don't wanna tell her straight out, just hint that I am, but subtly...Help me? Thanks lol