Git is a term of insult denoting an unpleasant, silly, incompetent, annoying, senile, elderly or childish person.
As a mild oath it is roughly on a par with prat and marginally less pejorative than berk. Typically a good-natured admonition with a strong implication of familiarity, git is more severe than twit or idiot but less severe than wanker, arsehole or twat when offence is intended.

The term is used by Graham Chapman in the Monty Python sketch "Argument Clinic".

The term is also frequently used by the character Derek 'Del Boy' Trotter in TV series Only Fools and Horses.