Ryan Garcia Slaps Streamer Kanel Joseph's Camera At Halloween Party

Ryan Garcia had ONE rule for streamer Kanel Joseph at his private Halloween party -- put the camera away -- so when Kanel kept rolling, KingRy wasn't having it ... and hands started flying!

And yes, the whole thing was streamed live.

Garcia and N3ON co-hosted a costume party in L.A. on Thursday, and the story goes that outside streams weren't allowed because the guys had sponsorship deals that prohibited others from streaming.

So, the champion boxer and party host walked up to Kanel and told him to stop recording. When the stream kept going, Garcia reached over and slapped the camera to the ground.

But that wasn't the end of the confrontation. Garcia turned to Kanel's security guard and slapped him, too, as party guests watched.

Joseph eventually got the hint ... but rather than staying, he just bailed on the party.

As for Garcia, he hasn't said anything publicly about the run-in.