The Fresh Prince Of Bel-Air: Reality Bites
Series 5 episode 3 from 1994.
Nicky goes to the mall to see Dougie the whale but Will ends up fighting with him and Nicky is upset.
To redeem himself, Will is about to tell his young cousin that it was just a man inside the costume when Santa arrives.
He warns Will about taking Nicky’s innocence.
Movie pages here.