The Grim Adventures Of Billy and Mandy Season 3 Episode 18 - Happy Huggy Stuffy Bears / The Secret Decoder Ring >When Billy finally gets a "secret decoder ring" in his Blasto Bits cereal, he receives a holographic message from a strange feminine creature who speaks about finding the "Secret of the Universe" in an abandoned mine shaft. All the other children of Endsville, also with decoder rings, race to the mine to be the first one to get the Secret. The entire effort is revealed to be a trap laid by Lubbermouth, a female worm-like creature from Grim's past who has a major crush on Grim, who wishes to free herself from the curse of guarding the Secret. When Mindy looks down at the pit, Lubbermouth pushes Mindy into the pit and she becomes the new guardian of the Secret and has to stay there forever.