SpongeBob SquarePants (1999)

S9E4 It's a SpongeBob Christmas!

Plankton plots to spoil Christmas in Bikini Bottom by using his special jerktonium-infused fruitcakes to turn everyone from kind-hearted to mischievous, transforming them into donkeys in the process. His ultimate goal is to seize the Krabby Patty secret formula. However, SpongeBob proves to be the exception, as his deep love for the holiday season grants him immunity to the jerktonium's effects, allowing him to remain his cheerful self amidst the chaos.