Animaniacs Easter Egg - MST3K in Animaniacs

In the "Potty Emergency" episode of Animaniacs, Wakko, Yakko and Dot go to watch Brain Eaters from Outer Space, wherein an alien attempts to eat its victim by catching her between two pieces of bread. As she runs over to the side of the spaceship, she opens the window and screams. Right above the very window is inscribed: "MST3K", referring to the series Mystery Science Theatre 3000, a favourite of the shows producers