Credit: Kevin Mazur/WireImage; Jim Smeal/BEImages; Chung Sung-Jun/Getty; Bryan Bedder/Getty

Katy Perry, Rihanna, Tina Fey and Lea Michele are among the stars who could get splattered in green slime at Nickelodeon's 23rd Annual Kids' Choice Awards this Saturday. Rihanna is slated to perform while the others will hand out awards in categories such as Favorite Couple, Favorite TV Show and Favorite Cartoon. Nominees with the most votes win, and kids (or kids at heart) can still vote for their favorite stars online. Tune in to Nickelodeon this Saturday at 8 p.m., to see who wins and, most importantly, who gets slimed!

Update: We'll also be seeing a taped message from First Lady Michelle Obama, who will be honored for her "Let's Move" campaign to cut childhood obesity.