Sketch comedy is interesting because it can sub-categorise any of the other categories.
Sketches are essentially, short jokes, and will often relate to situations where actions before and after the event are not important. We make assumptions and take things for granted:
‘This woman has a squirrel’s head’, ‘There are lizards coming out of the television’, ‘This man is to be executed;
We do not question these facts, but simply absorb them in order to understand the rest of the sketch.
In many cases, sketches will be repeated several times with slightly different outcomes or punchlines, enhancing their humour through repetition, and eventually taking us by surprise by breaking the conventions which we have become accustomed to through repetition.
‘The first five times, the man killed the rabbit. The sixth time, the rabbit killed the man.’