Some 3,000 youngsters decended upon Nickelodeon’s Sunset Boulevard lot Saturday for relay races, rock climbing and “slime bucket brigades” with celebs as part of the “Let’s Just Play” spec live-taping.

Rapper Master P came out in support of the cause, leading a celeb basketball team known as P’Poppers into victory in an all-star game against former Laker star John Salley‘s team. Master P emphasized the importance of education. “Playing is a form of meditation for youth,” he said.

“American Idol” runner-up Clay Aiken opted out of the basketball game and said he’d rather stick to singing. Performing along with Hilary Duff, Bow Wow and Nick Cannon, Aiken said the festival was more fun than working.

Also on hand: Frankie Muniz, Melissa Joan Hart, Ashlee Simpson, and Donovan Patton, along with hosts Olympic medalist Summer Sanders, Mati Moralejo and Brent Popolizio and Candace Bailey from Nick’s “U-Pick Live.”