The Superpower of Bi-invisibility.

Just like with the Harry Potter invisibility cloak , bisexual can walk around totally undetected. It's amazing really! Bisexuals can go to LGBTQ conventions and not ever even be noticed.

Even when you run around waving your arms shouting "I'm bisexual" people either see a straight or gay person. If you're in a relationship with a person of the opposite sex, people know you are straight. If you are in a relationship with someone of the same sex, people know you are gay. If you say, no, I'm bi, people laugh, or get angry, or pretend they did not hear and still see a straight or gay person. If you act the way people think gay people act and have been in a relationship with someone of the opposite sex, then you are a closet homosexual. If you have only been in relationships with people of the same sex and start talking about your sexual/romantic interest with someone of the opposite sex, then you are confused, or oversexed, or trying to fit into society.

And make no mistake about it, lots of bi people who have learned that their bisexuality is greeted only by negative, hateful, hurtful, negating, responses, are walking around clinging tightly to the safety and hell of their natural invisibility super powers - maybe even in your neighborhood, or workplace, or at your family Christmas dinner, masquerading as that nice gay boy or that sweet straight girl.
As my character Jim, in my novel "Love, Sex and Understanding the Universe" puts it: "I could even tell him the truth, point blank, and he still wouldn't know. I could say, "I read the gay papers because I'm bisexual and these issues concern me," and he'd laugh, think it an off-color joke, and leave it at that. I was invincible, and I knew it. Invincible, like invisible..."
Boo!