The girls revealed this fun fact to their fans in the behind the scenes video for Ariana's "Thank U, Next" film clip.
It happened when they were standing back to back about to film the Mean Girls "Jingle Bell Rock" dance.
"Remember when we ran out of lip gloss and kissed on Nickelodeon?" Elizabeth asked, to which Ariana replied, "I know! Guys, want to know a little-known fact?"
"When no one would hear us and we would be begging like, 'We need a touch-up please,'and they would be like 'rolling,' we would look at whoever was glossier at the moment, and to add more color, we would be like [makes kissing gesture], 'Let’s go,' and we would transfer the color," Elizabeth revealed. "That happened."
"That was really funny, I had forgot about that," Ariana added.
Now that's a real friendship.