Britney Spears -- Tyson Beckford Is A Freak On A Leash

Britney Spears made Tyson Beckford her bitch by strapping a leash to him and walking him up and down the stage for her audience to see ... and it looks like he loved it.

Brit reunited with her old "Toxic" music video co-star in Vegas during her Planet Hollywood show -- and there was a lot of leather, a lot of chains ... and a lot of Tyson on all fours.

After the "Freakshow" performance ... the Chippendale's headliner got more comfortable by stripping to cheers and screams in the crowd. Brit joined in too, but no stripping for her. No chains either.