Smurfer Upper Day is a day that the Smurfs observe in the cartoon show episode "Swapping Smurfs", where the Smurfs spend the day fixing up their homes. It is on that day that Lazy, who wanted to avoid participating in that day with his fellow Smurfs, discovered the Magic Swapping Well, and in it the Well Wizard, who started off as a benevolent being who simply allowed the Smurfs to swap whatever old thing they didn't want for something better, only to soon reveal his true nature when Grandpa Smurf, Hefty, and Snappy went into the well to get Sassette's old Smurfy Lou doll back from the wizard and were hypnotized instead. Papa Smurf knew that the wizard in the well was after the Smurfy Book Of Spells, in which there was a spell that could free him, so to prevent that Papa Smurf altered the book by having a special green page put in its place and tricked the Well Wizard into using the spell on that page, which caused the wizard to be sealed up inside his well and freed the Smurfs from his hypnotic spell.