Party like it's 1994! More than 20 years after All That first premiered on Nickelodeon, the cast of the teen variety show reunited at Stan Lee's Comikaze Expo in L.A. on Sunday, Nov. 1. And in a moment straight out of your '90s dreams, they broke into the famous theme song, "All That," originally performed by TLC.

Two generations of cast members — including Kel Mitchell, Lori Beth Denberg, Alisa Reyes, Mark Saul, and Angelique Bates — sang through the entire opening a cappella, complete with rapping and beatboxing. Mitchell, 37, who recently reunited with his Good Burger costar (and fellow All That alum) Kenan Thompson, even stood up and started dancing. 

"Fresh out the box, stop, look, and watch! Ready yet? Get set! It's all that!" they began, before joining together on the chorus.

Mitchell shared several pics and videos from the panel, including a group shot with his former costars and a clip of them all walking out onstage together.

"Super Awesome Day at #Comikaze15 at the #AllThat Reunion!!" he captioned one of the photos. "It was great meeting all of the Fans!! S/O out to Regina, Stan Lee, and the #comikaze15 staff, you guys are awesome!!"

Right before the turn up!! #AllThat Reunion #Comikaze15

A video posted by Kel Mitchell ???? (@iamkelmitchell) on Nov 1, 2015 at 10:38pm PST

As '90s kids no doubt know, All That ran on Nickelodeon from 1994 to 2005 and featured such future stars as Amanda Bynes, Nick Cannon, and Jamie Lynn Spears

Several of the cast members reunited last month at New York Comic-Con, where they told stories about their auditions and favorite skits, and even channeled some of their former characters.

Watch the cast sing the theme song above!

Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics, and more delivered straight to your inbox!