As a kid I used to be terrified of "Hviske" and "Tiske" - two elf dolls belonging to my middle school classroom. During the year these two 'nisser' with porcelain faces and wooden clogs were locked in the teachers drawer and every December they were taken out.
Being so-called 'teasing-elves' they were basically vicious little creatures causing rampage and mess all around them. Every day one kid was chosen to bring the two dolls home for one night. We were half scared and half amused whenever we entered the classroom and found the chairs and tables all mixed up. I think our parents and teachers had more fun bringing Hviske and Tiske to live than we had cleaning up after them...