First, 'Glee' (Tue., 9PM ET on Fox) had an entirely Madonna-based episode. Now, 'Grease' star Olivia Newton-John appears on the show. It all makes sense, we promise you. Although even if it didn't make sense, seeing Newton-John on 'Glee' would still be pretty cool.

Sue (Jane Lynch) has her "jazzercise" exercise video accidentally released for the entire world to see. Shockingly, the somewhat terrifying image of her dancing to the song 'Physical' becomes an unexpected hit. Then, singer Newton-John sees this remake of her song, and decides to help Sue make a new version of the video. Which is really something that you need to see for yourself.