'Mom' Stars Anna Faris and Allison Janney Celebrate Their Birthdays with a Pie Fight!


It doesn’t matter how old you get, or how famous you are — the Happy Birthday song will always be 30 seconds of awkwardness to endure.

But if you're Anna Faris and Allison Janney, the stars of CBS's hit comedy Mom, you'll find a way to turn your birthday celebration into a fun-filled (and extremely messy!) memory.

Last week, the cast and crew of Mom, surprised their two leading ladies with a birthday cake and impromptu song at the live-taping of an upcoming episode, and only ETonline has your exclusive behind-the-scenes look at the hilariously candid moment.

WATCH: Anna Faris Talks Possible Chris Pratt Cameo on 'Mom'

When Janney, who turned 55 on Nov. 19, and Faris, who turned 37 on Nov. 29., stepped out in front of their live studio audience, they were greeted with a gigantic chocolate cake, two pies, and a room full of excited fans.

After singing "Happy Birthday" to each other and successfully blowing out their candles, the stars decided to gift each other with a special present: a pie in the face! Take a look at our video above to witness all of the whipped-cream craziness for yourself.

Mom airs Thursdays at 8:30 p.m. on CBS.