When Les Dawson was interviewed on ‘Parkinson’ (a TV chat show), he said the following jokes.

Talking first about one of the places he used to do shows, it was “…a club so bad they didn’t laugh if they liked you, they let you live.”

It is this second one that grabbed my attention, about where he used to stay: “The room was so small, when I turned the light off, I was in bed before it went dark.”

This approach creates a logical contradiction in mind, whereby the size of something conflicts with the instancy we expect from turning off a light. If you think of the joke as a puzzle, you have to break the known rules of the Universe in order for it to work i.e. for it to be funny.