Rick is an androgynous male. Hes half masculine and half feminine. Both sides are attracted to women. Thus, Rick is a male lesbian AND a heterosexual male.
Sally to Joe: "Babe, do you want to go have sex?"
Joe to Sally: "After Joey kisses Pacey on Dawson's Creek. It's my favorite part."
Sally to herself: "Oh dear god, I am dating a lesbian..."