Peter, one of the main character in the series freezes his sister Judy using a voodoo doll he stole from one of their Jumanji adventures.
The voodoo doll was originally used by a witch doctor who revived Peter after he is drowned in a river, which then it is explained that the doll cures all and what's needed is a single strand of hair. Peter stole the doll and back in the real world, caused mayhem at the school and his home. Judy found out and attempted to stop him, but Peter uses one of her hairs on the doll and puts it into the fridge which caused Judy to turn to ice.
She is later reverted after another journey inside Jumanji.