American Idol Justin Guarini stars in a hilarious Diet Dr. Pepper commercial 03/30/2015 Justin Guarini is returning to TV -- sort of. Read More RELATED NEWS 'American Idol' Season 1 finalist Nikki McKibbin dies at age 42 Kelly Clarkson says her weight reflects her happiness -- "It's when I'm fat that I'm happy"Kelly Clarkson: "I wanted to kill myself" when I was "really skinny" TAGS: American Idol Kelly Clarkson Justin Guarini
