In an old monastery deep in the mountains in a fair country, a community of religious men grew their own food, and because the climate was warm, unlike that of Wales, they were able to harvest bananas and other tropical fruit. But the monks' regime was very strict and they were obliged to lock themselves in their cells every evening at sunset. One of the monks was a pervert and late one evening he lost his key and couldn't lock his door. He went searching for it on tiptoes and explored all the deserted passages and halls but he couldn't find it anywhere.
The following morning the community was mortified to learn that the bananas on all the trees had been eaten.
“This is the work of a monk key!” cried the abbot, “and it must belong to someone here. I will find out who!”
The pervert decided he might as well confess his guilt.
“Yes, it was entirely my fault,” he said. “I liked to spank my monk key and it escaped last night and obviously went on an eating rampage. But in my defence, the pun doesn't really work. If you try too hard to force a pun it'll simply go on strike, like a miner.”
“You're right about that. You're absolved,” said the abbot.
¶ Puns only work for themselves.