‘American Idol’: Judges Perform ‘Laverne & Shirley’ Theme Song (WATCH)

What would Simon Cowell say?

'American Idol' Judges - Season 14 (2015)

File this one under: Performances we never expected to see.

Music superstars Keith Urban, Jennifer Lopez and Harry Connick, Jr. broke out into song while taping auditions for the upcoming 15th (and final) season of AMERICAN IDOL.

Their collective tune of choice?  The theme to 1970’s sitcom LAVERNE & SHIRLEY.

Naturally cameras were rolling and today Fox decided to share this instant classic with the entire world.

What would Simon Cowell say?

AMERICAN IDOL returns January 6 on Fox.