She was on the Simpsons in "The Fight Before Christmas" where she played herself.
In this special, she is Moe's girlfriend and appears after Mr. Burns enters the Simpsons' home. She believes that the house (which the Simpsons told Moe to care of) is really a bachelor pad. She along with all the characters (as puppets) begin to sing "The 39 days of Christmas".
After the credits, She is last seen with Moe who is trying to kiss her, but is unable due to his height. He then decides to kiss her belly button, but is really kissing her vulva. A surprised Katy Perry reveals this to him and stops, but tells him to continue and continues kissing her vagina, much to her delight.