The Megalomanium was one of Jimmy's experiments seen in the episode "The Tomorrow Boys". It is a chemical that causes any living thing it touches to become mad with power. He tested it on a flower, and it turned it into a violence-craving demon that killed the flower next to it and it ten started to throw heavy objects at Carl and Sheen. This played a pivotal role in the episode Tomorrow Boys. Jimmy and Carl accidentally gave it to Libby for her birthday, and it caused her to become mad with power and take over the future Retroville as an evil dictator. Under her role, Jimmy was married to Cindy and forced to clean her mom's feet, Carl was an outlaw, Sheen was a dumpster diver, and Goddard was all rusted up and filled with broken parts.
After traveling to this timeline and witnessing it firsthand, Jimmy and friends were able to recover the Megalomanium from Libby's birthday party in the present and destroy it, erasing the bad future.