This Joke Has Been Used

(I overhear the following conversation in the pharmacy:)

Customer: “I’d, um, like some, er, suppositories, please. Sorry, but I’m not really sure which ones. They’re for my wife, who called out for me to get some when I was half-way out the door on an errand to do something else.”

Pharmacist: “Certainly, sir, let’s go and look for some. Here: would they be these?” *offering him a particular brand*

Customer: “Pff. Not sure. Could be; I know she suffers from the H word, but on the other hand…”

Pharmacist: “You can bring them back for a refund and replace them with the other kind.”

Customer: “What, even if…” *at this point he cracks up laughing* “Even if…” *and he’s laughing so hard he can’t say what he’s trying to say*

Pharmacist: *knowing exactly what he’s trying to say; it’s an old joke, but so funny she can’t help laughing herself* “…even if they’ve been used?”

(Both customer and pharmacist laughed like grade school children.)