Diddy: My Arm's in a Sling, But My Ass Isn't

Diddy was not the worse for wear Saturday night at Playhouse nightclub in Hollywood ... and there are no signs his surgery will derail the insanely successful Bad Boy Family Reunion tour.

The rapper had his 4th rotator cuff surgery 4 days ago, but he was already out and about ... in good spirits.

He's got time ... the tour starts in August.