A woman in her early twenties is confronted by her father. He believes she's a lesbian. She says she's not and that she'd do anything to prove it. Truth is she's not sure if she is a lesbian or bi or what. Her father tells her in order for her to prove she's not a lesbian she has to have sex with a guy and he has to watch them. She thinks about it and eventually agrees.
As she's having sex with the guy she acts like she's having fun but inside she's not into it, which gets her to think that maybe she really is a lesbian. When the guy is done with her she closes her eyes so she can relax. Then she feels herself being mounted again, but it's different. She opens her eyes to find her own Father naked and getting ready to have sex with her.
She starts to protest but decides to give this a try. She goes through the act of enjoying herself but is surprised to find that eventually she actually is enjoying things.
Weeks later she finds out that she's pregnant and wonders who the father is.