Short John is a term used to describe a type of men's clothing. It is a style of trousers that are cut off at the ankle, and usually have a cuff at the bottom. The term is derived from the fact that the trousers are shorter than regular trousers, and therefore look like they have been cut off. The term 'LAV' is an abbreviation for the word 'LAVENDER, ' which is a light purple color. This color is often associated with the Short John style of trousers.