US fans of The Simpsons have told CBBC Newsround that an episode with JK Rowling and Tony Blair in it was one of the funniest they've seen.
Nick, 14, said: "JK Rowling called Lisa a nice muggle and told her that the Harry Potter series was going to end with Harry Potter marrying Lisa."
Nicole-Leigh, 14, said: "Oh my gosh, the episode of The Simpsons with JK Rowling was great. For all you Brits, YOU GOTTA SEE IT!!!!!"
The episode will be on here in January.
