Phineas and Bart: A Christmas Crossover

In Phineas and Bart: A Christmas Crossover, the gang heads over to Springfield to spend Christmas with the Simpsons. meanwhile, Doofenshmirtz steals Mr. Burns' money to create a weapon to destroy Springfield.

"Too Young" Line
Homer: Aren't you a little old to save Christmas in Christmas?

Phineas: No, no I'm not.