Foster's Home for Imaginary Friends

When a hoard of imaginary Santas enter the house, Mac starts to believe that there is no such thing as Santa Claus. Bloo decided to try to prove him wrong, in hopes of getting the real Santa to deliver him more presents, so they go about trying several experiments that would logically prove Santa is real. Will Mac be able to regain his faith in Santa Claus or will this be the worst Christmas ever for Foster’s and Mac alike?