Joke from comedy legend Barry Cryer

I read a wonderful joke in The Guardian during the weekend, which appeared in Simon Hoggart's column. A man buys some LSD tablets and leaves them in a small bag at home on the kitchen table. When he comes back, the bag is empty. He turns to his mother and says "Did you find any pills in that bag?"  "Never mind those bloody pills," says his mother, "there's a dragon on the shed!"