In the inaugural episode, Jimmy Fallon gives the four kid hosts -- Mykal-Michelle, Recker, Olivia and Dylan -- tips on anchoring a talk show, including how to shoot lasers out of their eyes.

Dancer, singer and actress JoJo Siwa joins the show, shares why she's proud of being her authentic self this year and plays hilarious and intense house games as part of the JoJo-lympics.

Questlove and Black Thought - members of "The Tonight Show" house band - join to reminisce about how they met in high school and the key to the perfect birthday party before a surprise performance by Dylan and Recker.

Popular online creators and well-known pranksters Brent and Lexi Rivera, Jeremy Hutchins and Pierson Wodzynski of AMP World join the show for an epic, legendary games episode.

"NBC Nightly News" anchor Lester Holt joins the show and shares a funny story about how he couldn't stop giggling during a broadcast, plays a hilarious game of Real or Phony News and partakes in an awesome "Mayhem" party.

Popular online creators Charli and Dixie D'Amelio join the show and reveal the best and worst parts of working together while being sisters; the hosts compete to see who can make the best ice cream sundae without using their hands.

Magician Dan White stops by the show and performs some crazy and unforgettable magic tricks; one of the hosts gets cut in half and another gets pied in the face.

"Frozen" actress Kristen Bell joins to talk about the inspiration behind her new book and to show off her weirdest talent; the hosts play a silly game of "Bell or Not Bell"; Egg-braham Lincoln stops by with some jokes.

Activist, model and star of "Grownish" Yara Shahidi joins the show to talk about her cool karate skills; pointless PSAs, mayhem times a million and a hilarious game of history trivia.

Real-life astronaut Mike Massimino joins the show to talk about being in space and plays a fun game of Globe Grab.

Singer-songwriter and "Clash of the Cover Bands" host Meghan Trainor plays a hilarious game of All About that Bass and shares her favorite vacation memories.

Yo-yo world champion Gentry Stein shows off some of his most awesome tricks, plays a crazy game of Velcro Madness against host Recker and joins the most yo-yo-tastic mayhem party yet.