The Adventures of Jimmy Neutron, Boy Genius
Granny Baby / Time Is Money
S1 E4:
Jimmy's Granny comes to stay while Judy and Hugh are off on a third honeymoon. Jimmy, concerned by her ailing health, gives her his new youth tonic. However, the potion works too well - Granny ends up as a talking baby! Through the wonder of time travel, Jimmy goes 15 years into the past to a time when his parents were swinging sweethearts. Jimmy's investment tip changes the future so that the Neutrons become fabulously rich - but with unintended consequences!