CeeLo Green: 'Happy' Was His Song FIRST – Regretting Passing on Pharrell's Hit?

It could have been CeeLo Green's voice stuck in your head singing the song "Happy," but he tells TMZ he has no regrets on passing on the most popular song around.

Our photog spotted Green at LAX on Tuesday, where we asked him about the hit song. Turns out, CeeLo recorded the catchy track first, but ultimately his label decided not to release it. You know how that turned out ...

CeeLo gives the diplomatic answer, but the way he pauses every now and again makes us think he realizes he passed on a goldmine.

Also be sure to check out CeeLo's joke about his back. Pretty funny ...