Britney Spears is officially part of the "Jackass" crew -- because last night, she made it look like she took part in one of the gang's dirtiest deeds.

As part of her appearance on "Jimmy Kimmel Live" on Tuesday, Britney filmed a sketch showing her "deleted scene" from "Jackass 3D" where she performed a stunt called "Poo Cocktail Supreme" -- the flying porta-potty stunt Steve-O did in the movie.

Warning: The clip has a few gross-out moments if you watch it thinking it's real ... but it's not. So enjoy!

MTV also debuted the trailer for their special, "Britney Spears: I Am The Femme Fatale," check that out below!