SpongeBob SquarePants and his friends are going live action in a new one-hour special: SpongeBob’s Big Birthday Blowout.

For the very first time, the voice cast behind SpongeBob (Tom Kenny), Patrick (Bill Fagerbakke), Mr. Krabs (Clancy Brown), Sandy (Carolyn Lawrence), Squidward (Rodger Bumpass), and Plankton (Mr. Lawrence) will play human versions of their animated characters. Premiering on Friday, July 12 at 7:00 p.m. ET/PT on Nickelodeon, the special will mix live-action scenes with animation and feature a legendary guest star: Knight Rider‘s David Hasselhoff.

Hasselhoff, who previously appeared in The SpongeBob SquarePants Movie (2004), will appear as himself, once again donning his famous Baywatch garb.

The Mighty David Hasselhoff and his Pirate friend

“I experienced the world of SpongeBob first-hand when I appeared in The SpongeBob SquarePants Movie, which was an amazing experience,” Hasselhoff says. “After making that cameo, kids around the world recognized me from the movie. How awesome to now come back to be part of the 20th-anniversary special. I got to interact with Tom Kenny and SpongeBob. It also was a heartwarming tribute to Steve Hillenburg. Happy 20th SpongeBob. Hooray!!”

Additional guest stars include Kel Mitchell (All That), Jack Griffo (The Thundermans) and Daniella Perkins (Knight Squad).

Tom Kenny and David Hasselhoff

“Steve Hillenburg gave me the gift of a lifetime when he asked me to voice his porous alter ego, SpongeBob SquarePants,” Kenny adds. “He changed my life and all of our lives. To reach the 20-year mark is a huge milestone and we wanted to celebrate by throwing a big party Bikini Bottom style. SpongeBob only comes up to the surface world on special occasions, and this time one stop on his journey is The Trusty Slab restaurant. Stepping on the set and acting alongside my friends and fellow cast members was a true out-of-body experience. Fans are truly going to love it.”

In the new special, Patrick and SpongeBob journey to the surface world, arriving at the Trusty Slab restaurant just in time for the lunchtime rush. Meanwhile, the Bikini Bottom residents set up a surprise birthday party for SpongeBob in his absence.

Photos: Nickelodeon