Don's Fountain of Youth (1953)
The boys are more interested in their comic book than the sights on their Florida vacation. When the car breaks down next to the spring "mistaken for the fountain of youth", Donald decides to have some fun with his nephews and hides the part of the sign saying "mistaken for". As baby Donald, he starts shredding their comic book and generally acting like a spoiled brat. But when he decides to pretend he's turned into an egg (borrowed from an alligator), he's in for trouble he hadn't bargained for once the gator finds out.