The Fountain of Youth

That's the Fountain of Youth from 

Ducktales Episode called "Sweet Duck of Youth". 

Scrooge McDuck looked at his Reflection so young,

the old Duck looked at his Reflection so young, 

and then Launchpad McQuack looked at his Reflection so young

that's because the Fountain of Youth doesn't make the Grown-ups young 

it makes the Grown-ups' Reflections young. 

The Reflections of Huey, Dewey, and Louie were Eggs 

when they looked at them with the young Reflections of 

Scrooge McDuck and the old Duck.
Ponce de Loon was a Parody of Ponce de Leon.
According to the Spanish Mythology, 

Juan Ponce de Leon the Conquistador 

and his crew became the first recorded Europeans to set eyes on Florida 

and they made this discovery while searching for the Fountain of Youth, a magical Water source supposedly capable of reversing the aging process and curing Sickness 

on Wednesday, April 2, 1513.