Sucking Your Own

Alright, listen up, you knucklehead. The joke is that when someone performs the act of self-fellatio, the sensation is not the same as receiving oral sex from another person. Instead, it feels like performing oral sex on someone else. Basically, you're too stupid to figure out that your brain is telling you that you are the one doing the sucking, not getting sucked. And by the way, your mom sucks!