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.

"Annie Live" stars Celina Smith and Tituss Burgess talk about their upcoming musical and play the craziest game of Box of Lies; a visit from a caveman, unboxing galore and Recker gets very confused.

Olympic skateboarding champion Bryce Wettstein kickflips into the show and answers a jaw-dropping question from a surprise guest; a crazy game of All Ball and the silliest, skateboard-iest mayhem party yet.

"Saturday Night Live" legend and "Kenan" star Kenan Thompson joins the show to talk about his favourite impressions and a possible "Good Burger" sequel; a crazy game of What's Behind Me and a whole bunch of plopping.

YouTube star Nastya and online looping genius Marc Rebillet join the Pajama Party episode.

Miranda Cosgrove of "iCarly" joins the show for some random dancing; actor Matt Damon answers the silliest questions from the What?! Bucket; Twitch superstar Ninja stops by.

"Glee" star and author Chris Colfer joins the show for a lightning round of questions with Young Dylan; National Spelling Bee champion and Guinness World Record holder Zaila Avant-garde gets a surprise from a special guest.

Actors Matthew McConaughey and Nick Kroll join to talk about the inspiration behind their "Sing 2" characters; adults spell things, two of the hosts have a Corn-Off and the show examines the origin of yogurt.

Dancer and actor Pressley Hosbach joins the show to talk about her time on "Dance Moms" and "Stage Fright"; Pressley takes a spin on the Random Dance Generator and unleashes a whole lot of mayhem.