to go out and enjoy yourself in the evening, often drinking a lot of alcohol and dancing Jack finished his exams today so he's gone out to paint the town red.
Go on a spree, as in Whenever they go to New York they want to paint the town red. The precise allusion of this term is disputed. Some believe it refers to setting something on fire; others point to a vague association of the color red with violence. [Late 1800s]