It was so fun, Fallon tried to mimic it with a little note that was kind of a fail.

Her musical-impressions reign didn't end there. After Fallon's pretty good take on Louis Armstrong's robust voice on the Mister Rogers' Neighborhood theme song, the "Confident" singer showcased her skills as a singing rapper. She channeled "Trap Queen" rapper Fetty Wap for an awesome rendition of "Twinkle, Twinkle, Little Star." What worked about it was Lovato's use of Wap's "Come My Way" rhythm to both rap and sing the classic children's tune.

Fallon came through with a Dave-Matthews-Band-inspired version of "I'm A Little Teapot." Though he claimed he didn't know what to do, he must have practiced in the dressing room, because he nailed the calmness of the band's lead singer, Dave Matthews. Lovato told Fallon his rendition was "perfect."

What was also perfect? Lovato, like Ariana Grande before her, channeling her inner Christina Aguilera. Xtina has some serious pipes, and in case you forgot, so does Lovato. She may have mimicked Aguilera in the bathroom as a child, because she got Aguilera's difficult voice down pat. Lovato's version of the SpongeBob SquarePants theme song earned her a standing ovation from Fallon.

The host then said "game over." No way he could top that one.