This one is taken from a GCSE exam paper my wife marked last week.
Three old ladies sat on a park bench.
The first one says, "I remember when we used to grow all our own food, and we had onions this big!" cupping her hands the size of a large onion.
The second one says, "I remember growing cucumbers this big!" holding her hands apart the size of a large cucumber.
The third says, "I may be deaf, but I know the bloke you're on about!".
Sadly, he didn't gain any extra marks