Similar to that, my buddy asked a child at the counter
"Are you having a nice time with your grandfather?" before he interrupted
"I'm her father actually."
Funniest i have but not as good as jebus was when i worked in a supermarket in town and there was a security guard, Jack in the mall always complaining that his job is boring and he never gets action. One night there was a few young fellas robbing slabs of drink so himself and the supermarkets guards dived on them, wrestled them to the ground and called the gardai. I looked out and while all the young fellas were pinned down, Jack was bouncing a walkie-talkie off his fellas head repetitively.
His manager came around the corner saying "What the **** are you doing?"
He said "this young fella was walking with a crate of drink."
His manager said "Get up, leave him go, go home and don't bother coming in next week."
It was funny watching the thief hang around while Jack protested his case.
After a while, the thief started strolling off with the drink and the manager said "What the **** do you think you're going?"
The thief said "It's alright I'll pay for it." and walked off towards the tills. They just barred the rest of them.
Didn't want any case against them i suppose.