Shops are good.

"Can I have that [insert whatever]?"

"Sorry we don't have any."

"You do you have one on show!"

"Sorry that is for display purposes"

"Why have one on display if you don't have any...?"

Usualy confuses them around that point.

Best recently was the caretaker of our building. The lock to the car park was jammed and no one could get in from outside. You could get in by walking round to the car entrance and walking up the ramps and you could get out through said pedestrian door.

"Why don't you tape the latch open?" I asks.

"Can't do that!" answers the jobsworth. "It is a breach of security."

"But..." I began. Decided to give up rather than start:-)

Cheers

DtG