Britney Spears Makes 'Bachelorette' Star Her Dance Slave

Britney Spears might be taken but that's not stopping her from picking famous, freshly single bachelors out of the crowd at her Las Vegas show.

"Bachelor in Paradise" star Josh Murray, who also won Andi Dorfman's 'Bachelorette' season, got the "Slave 4 U" serenade from Brit at her Wednesday night concert. It's a part of the act ... Brit picks someone in the crowd, dresses 'em up in straps and makes 'em dance.

Lance Bass has done it, but doesn't look like Brit knew she had a celeb onstage ... based on what she says to him at the end of the routine.