Adam Levine and Christina Aguilera may sound like a perfect pair in their new single -- but on the set of "The Voice," it might be a different story!

"She's a pain in the ass," Levine joked to Conan O'Brien last night on his TBS show, "but she's my pain in the ass. I love her."

Responding to gossip that she's a diva on set, Adam added "We love her, she's super talented. We're all pains in the asses!"

Aguilera wasn't the only one Levine poked fun at -- he also took a jab at Simon Cowell and his tight wardrobe, saying the former "American Idol" judge may want to ditch the black V-necks for "a kimono."

How do you think they really get along on set? Sound off below!

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