That reminds me of one of my dad's from when we were kids:
The Queen is visiting a 'mental hospital' sees this perfectly normal man working in the garden with a group of obvious patients, 'You must be the gardener' she says, 'No ma'am, there's nothing wrong with me but they won't let me out'. 'I'll have a word' she says.
Later as she is leaving, a plant pot comes flying by, just missing her and a voice shouts 'You won't forget will you?'