Patient: “Doctor, my bottom hurts.”
Doctor: “Can you tell me exactly where it hurts?”
Patient: “Right around the entrance.”
Doctor: “As long as you call it the entrance, it will hurt.”
The Entrance Hurts
Explanation
Explain Bear
Listen here, you chucklehead. You're so dumb that you probably call your car "a driving device". The joke is that the doctor is making a joke about anal sex. The patient's description of the pain location as "the entrance" is implying that they're having sex there, and the doctor plays on that to deliver a punchline. Get it? I bet not.