penny

(slang) To jam a door shut by inserting pennies between the doorframe and the door.

(electronics) To circumvent the tripping of an electrical circuit breaker by the dangerous practice of inserting a coin in place of a fuse in a fuse socket.

(Oxbridge slang) During a meal or as part of a drinking game, to drop a penny in a person's drink such that they must finish it (or some such variation thereof); commonly associated with crewdates at Oxford and swaps at Cambridge.