This is very funny to me!
When I was a kid I was thrown into a dyer at the laundry mat on my way home from school. The kids that did it were in high school and I was in 4th grade. They wouldn’t let me out of the dyer until I told them I would give them 75 cents every day for the rest of the school year(this was a long time ago). I almost suffocated in that dyer as the brats actually put a dime in it and let me roll around in it like a piece of wet laundry. They stood in front of the door so it wouldn’t open up as I tumbled around in it. It was horrible! I have never forgotten that. Oh and I told my mom right away and she went to kick some bratty asses….or talk to their parents anyway. They never hurt me again.
After that happened to me I always went to the rescue of anyone I thought was being bullied. I became an angry kid for a very long time, but I saved some other children from being tortured!

From what I remember about bullies when I was a child this will just make the bully mad. Which will most likely get your child beat-up. If you know that your child is facing a bully you need to talk to the adults at school.
I think they are funny if you are just doing this to make your child laugh by shocking his/her friends. This is a cute idea for halloween.