Christina's getting 'Dirrty!' Christina Aguilera added a little spice to The Voice on Tuesday, March 1 — by locking lips with competitor Kata Hay after she declared the singer her first-ever "girl crush!"

Feisty Hay, 28, from Tulsa, Oklahoma, had already stood out from the crowd by running straight at Adam Levine following her killer blind audition, and giving him an enthusiastic kiss on the cheek.

But having returned to her spot on the stage, the fiery redhead declared that Xtina had actually been the object of her affection for many years.

"You were my official first girl crush," Hay, whose girlfriend was watching from backstage, told the 35-year-old singer. "You're so freaking beautiful in person!" she exclaimed.

"You're so freaking beautiful! Should we just make out now because I was your first girl crush? Let's get it over with so we can get to work," Aguilera responded.

As Pharrell Wiliams did the best shocked face ever, Hay rushed over and locked lips with Aguilera, leaving the male judges literally drooling on the floor!

"If you pick me, there's more of that to come," Aguilera promised. And it worked!

Watch the hilarious video above and see Williams' unforgettable reaction to his co-judge's unexpected makeout session!

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