- (intransitive) To become insane.
- (intransitive, idiomatic, followed by "and" and a second verb) Used to indicate that the second verb represents an action that is out of character.
- Let's go mad and have a bottle of wine with our lunch.
- (intransitive, idiomatic, usually as a past participle and preceded by a noun) To reach an excessive or ridiculous level.
- Why should we ban smoking on college grounds? Surely that's political correctness gone mad?
to become insane — see go nuts
to do something that is out of character