I tell that one as a little boy going into the frozen food shop, Bob:

Little boy to the man in the shop: "My mum says can I have a packet of Birdseye pissoles, mister."

Man frowns in puzzlement, then a smile spreads across his face: "Aha, little boy, I know what it is you want, but it's an R, not a P!"

"OK then, mister, please can I have a packet of Birdseye arseholes..."