This guy suspects his girlfriend is cheating on him, but he needs solid proof that she's a fucking slut. That's why he has her tied and blindfolded and lets his friend drill her slurping pussy to see her reaction when she finds out who's actually fucking her. She makes it look like she's shocked and unwilling at first, but then her slutty side takes over and she enjoys sex with a total stranger as well as a messy cumshot like a real whore.
