By now, you may have seen the celebrity Elf on a Shelf meme, a.k.a. Instagram posts of stars like Reese Witherspoon, Jennifer Garner and Elizabeth Banks photoshopping themselves with things that rhyme with their name. (For example, a picture of John Travolta and Olivia Newton John in Grease on Witherspoon’s shoulder a.k.a. “Grease on Reese.”)