Kelly Clarkson just gave Demi Lovato the "BEST BDAY GIFT EVER!!"

On the same night that Kelly emotionally announced that she was "totally pregnant” with her second child, she decided to give her friend a b-day present ever: a cover song.

"It's one of my girls' birthdays tomorrow -- when I say my girl, I mean Demi Lovato. It's Demi's birthday tomorrow," Kelly told the screaming crowd. "And she's always been such a fan, she's so supportive and so cool... she's just killing it. I thought I would, for her birthday, sing her new single, 'Cool For The Summer.'"

Kelly, who was performing her show Piece By Piece in Los Angeles, slowed down the up-tempo single, turning it into a smooth, sexy ballad.

Demi, who is celebrating her 23rd birthday, got wind of the performance and took to Twitter to thank Kelly for her rendition, which left her in "literal tears."

Hopefully, this kickstarts the long-awaited collaboration between the two singers. Back in March, Kelly promised us that these two would work together, and with Demi's album hopefully coming out this fall, there is no time like the present.

“We almost got to work together, but I was pregnant and she had asked me to sing. I totally was down, but it just didn’t work out,” Kelly explained this week to MTV News. “She was touring, I was super pregnant and not feeling well and it didn’t work out this time, but it totally will. … I love her; she’s so sweet. Every time we see each other, she’s always like, 'Kelly Clarkson, she’s so nice, and so awesome, we’re both Texans.’”