"Don't you think I'm going to cum inside you with my sister right beside us?" the narrator asks. He's not joking, and he's pretty sure that his sister's "first sexual experience" was with him. The narrator is all, "I love every part of you" . But then he realizes that the guy's just "casually" having sex with his sister, and that's it. He can't stop thinking about how awesome his sister is and how much he loves her. He wants to tell his sister about it, even if she doesn't end up marrying him.