What does "egg in our shoe" mean? Is it an idiom?
"Egg in our shoe" is not an idiom, however "beat it" is. "Beat it" means to leave a place or to go away. It is also used in baking to refer to whisking an egg. So this character is just being silly and saying "put an egg in our shoe" in reference to the fact that you "beat" an egg and they are about to "beat it. This is not a usual phrase and is just something this character has made up.