Don't mess with A$AP Rocky's clothes!

The famously fashion-forward MC bailed on a concert in Germany on June 6 after a fan allegedly snatched his Supremes cap -- and it's all on video.

During a performance of A$AP Ferg's 'Work (Remix)' with his A$AP Mob, Rocky was interacting with the crowd when his vintage Supremes cap was stolen from off of his beautiful head. This didn't sit well with him at all.

"Who took my s---?" he asked the crowd incredulously. "I came to party with y'all, give me my hat so I can [continue]. That's a one-of-a-kind hat!"

Dat PMF even promised no repercussions to whoever stole the cap -- he just wanted the darn thing back on his head. "We ain't gonna f--- you up, just give me my s--- back," he pleaded. But then it got a little intense: He wouldn't let one fan who was headed to the exit get out, telling security, "Yo, stop that guy over there from leavin' ... don't let nobody leave."

When the hat still didn't surface, he griped, "It's either that, or I ain't partyin' in this mothaf---er anymore." In hopes of the show going on, the audience started to chant "bring it back," but the hat still never turned up, leaving the Harlem native furious. "Nobody know nothin', huh? Germany, it's been good. Thank you; I'm out this b----. Peace!"

Moral of the story? Don't steal from A$AP Rocky if you want to hear him rap.