I faced off against Matt Stonie in a giant Fruity Pebbles cereal bowl challenge. Thousands of calories, endless sugar, and one crazy showdown—who do you think came out on top?

Try pastry chef Christina Tosi's quirky cereal combinations. Christina Tosi with her Kellogg cereal combos. Stefanie Tuder/ABC — -- Mad cereal scientist (aka pastry chef) Christina Tosi has ...