The castmates also joined Jimmy Fallon in a sketch titled "Slow Clap Soap Opera."

Ariana Grande is making a splash with her performance in Focker-in-Law , but no such thing ever occurred at Boca Aquarium — though she had Robert De Niro and Ben Stiller fooled.

In a game of “True Confessions” while visiting The Tonight Show Starring Jimmy Fallon on the Sunday (Nov. 8) episode, the pop star successfully convinced her A-list castmates — who each took turns trying to convince the others that a false memory was true, or vice versa — that she once accidentally plunged into a “giant fish tank” while visiting her hometown’s aquarium in Florida.

“I was little and clumsy,” she told De Niro, Stiller and Fallon — who was less convinced by the story but ultimately fell for the deception — while fudging details about her older brother, Frankie, scuba diving in the tank as she supposedly looked on at the age of 4.…