MGK Celebrates 29th Birthday with Pete Davidson & Hot Chicks

Machine Gun Kelly knows what time it is ... and not only because Pete Davidson and comedian John Mulaney got him a Rolex for his 29th birthday.

We got MGK and Pete leaving TAO Monday night in L.A. where they were celebrating with friends. Kelly and Pete were toking cigs and posing for pics when our guy asked Kelly what he got for his birthday.

Check out the clip ... MGK couldn't wait to show off his new classic timepiece. He also couldn't wait to invite our camera guy onto his party van ... much to everyone's delight.