Nicole Richie is a self-proclaimed Britney Spears supefan! (She even engaged in a dance-off to Brit's 'Slave 4 U'!) Nevertheless, we were still surprised to see the TV personality appear onstage during Britney's 'Piece of Me' show in Las Vegas on Tuesday night (Feb. 18).

Thanks to a fan (who had a really good seat, btw!), there's footage of Nicole dancing with Brit + Co. during an S&M-themed performance. Although the sound quality is so-so, you can tell Nicole is making the best of a semi-awkward situation. And, hey, who wouldn't want to share the stage with Britney?

Nicole clearly looks ecstatic in the Instagram pic she posted of the two hugging onstage. Awww!

You can watch it all happen in the video below, but be warned it's NSFW.