The game, on Wednesday, was moderated by Steve Higgins and involved Vergara and Fallon having to answer multiple-choice questions.
The actress and late night host were given three cupcakes for each question representing A, B or C. Vergara and Fallon then needed to bite into the cupcake they think represented the right answer, however, a wrong answer would result in them biting into a cupcake with a nasty, mystery filling.
Vergara and Fallon both guessed wrongly that Simon Cowell never signed the Teletubbies to his record label, causing them both to bite into a cupcake with garlic-filled hummus.
"I mean who did this? Who decided this?" Vergara said after being grossed out.
"Spitting it out is not enough," she continued.
Fallon got the second question right about students with the third highest GPA being called a historian, while Vergara ate part of a cupcake full of corned beef hash.
The duo continued to get wrong answers, resulting in them eating cupcakes filled with tomato sauce and then vegemite.
"You're going to make me hate cake forever!" Vergara said.
Vergara is returning to the judge's table for America's Got Talent Season 16, which premieres Tuesday on NBC.