My school had Parent-teacher conferences and Friday off. So we all dressed up in our costumes on Wednesday.
I was the wicked witch of the west, AKA "Elphie" AKA I made my kids call me "Miss Wicked" and wouldn't respond to "teacher" or "Miss Shumway."
I acted in character all morning. I whacked each child with my broom, asking them what they were dressed as. I purposely locked the classroom door so that when kids left the classroom (for the restroom usually) they'd be locked out. So I would see them knock and try to get in through the small glass window on the door. And I would point to them and cackle my high witch cackle for a few seconds before I let them in. They loved that. I had a lot of kids wanted to go to the bathroom.
We moved our desks to the side and had a fashion show to techno music. and listened to the "Wicked" sound track all day.