The ridiculous and wonderful rainbow hat

"When Riley Zimmerman needs help pulling off the greatest prank the Hopewell Elementary has ever seen, the magical Locker 37 . . . grants her a ridiculous and wonderful rainbow hat that clones anyone (or anything) that wears it. With the help of a bunch of Riley clones, an untrustworthy bully, and ten thousand Ping-Pong balls, can Riley set up the most epic prank in Hopewell's history without losing her friends in the process?"--Provided by publisher.