do one's thing

or[do one's own thing] {v. phr.}, {informal} 1. To do what one does well and actually enjoys doing. * /Two thousand fans paid $15 each to hear the rock group do their thing./ 2. To follow one's bent; for example, to be engaged in left-wing politics, some sort of meditation, or use of drugs (particularly in the sixties). * /The hippies were doing their own thing when the cops came and busted them./ 3. To be engaged in an unusual activity that strikes others as odd. * /Leave Jim alone, he's just doing his own thing when he's standing on his head./