Mike Epps -- Violence at Comedy Show ... Man Down (VIDEO)

Mike Epps' comedy was so brutal this past weekend, a guy was left bleeding and unconscious.

Epps was performing Friday at StandUpLive in Phoenix when he started clowning a guy in the front row for wearing a flannel shirt, saying he looked like the guy from Hootie & the Blowfish.

Everyone laughed but the doppelgänger, who got so PO'd he stood up and began yelling back at Epps. Security closed in, the guy stood up to leave and got jumped by some guys in the crowd. One witness says he saw someone sucker punch the guy.

We got video of the aftermath ... the guy is out cold on the ground and clearly hurt. Cops are investigating.

7:30 AM PT -- Mike apologized "to all my fans and anyone that got hurt at my show!" I never hurt anyone I was just doin what I do cracking jokes."