If you're a fan of cheesy '90s pop, be prepared for the following video.
Britney Spears, as you may know, is still in residency in Las Vegas with her 'Piece of Me' show - and is even rumoured to be extending her run by a further two years.
Meanwhile, her fellow popsters Backstreet Boys recently began their own residency in Sin City, and it seems that one of the boy/man band found his way onto Britney's stage the other night.
Howie D from BSB made an appearance during her song 'Freakshow', basically taking on the 'sex slave' role that an audience member usually would for the routine - and he even got a signed t-shirt for his troubles.
Watch it below: