Doctor
Explanation
The Joke
A man visits a doctor's office and announces: "Doctor, I have friction burns on my penis from too much sex." The doctor responds professionally that she'll need to do a biopsy to be sure. The man then says, "Oh, that won't be necessary. I'm not here for medical advice." Confused, the doctor asks, "Then why are you here?" The man pauses, addresses her formally as "Mr. Franck?" -- and the final panel reveals the patient is now sitting across from a lawyer, delivering the exact same opening line: "Lawyer, I have friction burns on my penis from too much sex."
The joke is that the man isn't seeking medical treatment at all. He is visiting various professionals solely to brag about his sex life. He has no actual medical concern -- he just wants an audience for his boast. The reveal that he's doing the same thing to a lawyer (and presumably every other professional he can find an appointment with) elevates the joke from a simple misdirection into a portrait of pathological bragging.
The Humor
The comedy works through misdirection and escalation. The setup appears to be a standard "awkward doctor visit" joke, but the punchline subverts expectations entirely -- the man doesn't want help, he wants witnesses. The formality of a professional appointment makes the bragging even more absurd; he is literally paying for consultations just to tell people about his sex life. The final panel, showing him repeating the routine to a lawyer, implies this is a pattern that extends to every professional in town, transforming a one-off gag into a commentary on a particular type of insufferable person.