Originally published on ProWrestlingSheet.

Former WWE Champ CM Punk was looking proud to be guilty last night in Chicago ... "Guilty By Association" that is -- and it's all on video.

Punk -- who's currently signed to a UFC deal -- joined his friends H2O on stage Thursday night at Reggie's and gave the crowd a quick taste of his vocal skills.

This ain't the first time H2O have jammed out with the Voice of the Voiceless, he's been known to join in when attending their shows.

Still no word on a date for CM Punk's UFC debut. Back in October, it was announced he had a shoulder injury that would postpone it from happening.

Punk's singing clip is quick, but it left everyone with a solid memory to get home and go to sleep with.