When I was a kid we had a whole school class who decorated the town just befor Halloween. Everyone thought it was funny (will maybe some older people didn't) but the rain came a few days later and washed it all way.
When my son was a senior in high school he had a shop class. The teacher was very good. The kids learned to take a car apart and put it back together again. You got it! thats just what they did. Only they decided to take it to the roof of the school and then put it together. Imagian everyones supprise in the am when they came to school . After pictures it was taken apart and taken down. No harm done. Good teacher and great bunch of kids.