mess around

mess around  {v. phr.}
1. To engage in idle or purposeless activity.
Come on, you guys, — start doing some work, don't just mess around all day!
2.  {vulgar}
To be promiscuous; to indulge in sex with little discrimination as to who the partner is.
Allen needs straightening out; he's been messing around with the whole female population of his class.
Compare: FOOL AROUND.
Categories: verb vulgar