Mariah Carey left the cast of "Schitt's Creek" tongue-tied after she surprised the actors during YouTube's Dear Class of 2020 graduation special. Eugene Levy, Catherine O'Hara, Daniel Levy and Annie Murphy – playing their beloved characters Johnny, Moira, David and Alexis Rose – came together virtually to sing Carey's iconic song "Hero" in honor of all the teachers and students who have prevailed during the pandemic.