When she says she wrestles, so you pull out your dick and she punches it.
Wrestler Surprise
Explanation
Explain Bear
Alright, listen up, nimrod. This joke is all about playing on expectations, you see? The setup makes you think it's gonna be a romantic or sexy situation, but BAM! It takes a turn for the worse. The punchline is unexpected and, honestly, pretty messed up. Your brain is smoother than a bowling ball, but try to keep up.