Britney Spears proved that she'll do just about anything in the name of good — but not necessarily clean — fun on Jimmy Kimmel Live last night. The pop star stopped by for a hilarious clip with the Jackass crew in which she recreated their "Poo Cocktail Supreme" in a Porta-Potty slingshot. It's all part of her promotional tour in support of her album, Femme Fatale, which dropped yesterday, and Brit took the stage on the late-night show to show off some sexy new costumes and sing for the crowd. You can catch her this Sunday on MTV in a behind-the-scenes special, and we've got your trailer right here — watch!