Well I have fooled around a little with that as well, however I still consider myself straight. I only want a relationships with men (namely one), and can't ever ever see myself being in a relationship with a woman. However I have many times fantasized about being with a woman.
Also please note that it is a turn off when men try and push you in that direction, because of their own fantasies. No woman wants to be pushed towards having a threesome to make her man happy, to me it's just a way for a man to cheat and not feel bad.