[7000rpmisheaven]

I didn't get involved in any of the senior pranks at my school. But here are some that I heard about

One year the seniors got a cow (don't know where they got it from). At our school we have a set of stairs that go up to the roof. Well cows can walk up stairs but not down. Upon finding a cow on the roof the school administrators had to get a crane to lift it off.
There was the prank with the pigs. You get 2 large farm animals. In big letters number the animals 1 and 3. When the police come they will have to spend extra time trying to find # 2.

Streaking is always funny.

One year the seniors released a few thousand crickets they got from a pet store into the hallway between classes.

I forget what they drew but one time they drew on the football field with a roto-tiller.