 Complete the following phrase:  A joke cycle is a collection of jokes about a single target or situation which displays consistent narrative structure and type of humour. Some well-known cycles are elephant jokes using nonsense humour, dead baby jokes incorporating black humour and light bulb jokes, which describe all kinds of operational stupidity. Joke cycles can centre on ethnic groups, professions viola jokes, catastrophes, settings ...walks into a bar, absurd characters wind-up dolls, or logical mechanisms which generate the humour knock-knock jokes. A joke can be reused in different joke cycles; an example of this is the same Head  Shoulders joke refitted to the tragedies of Vic Morrow, Admiral Mountbatten and the crew of the 