How about the journey of a bouncing ball?

I made a flash cartoon for school about why you shouldn't play with scissors. It was pretty cool, my partner and I incorporated sound and plenty of those long keyframes that created smooth, perpetual movement. I also made part of another that involved a sword flying into a room and two guys fighting.

Just look at an object and make a story based on something that object isn't supposed to be doing. LIke the TV coming to life and chasing a boy through his house trying to eat him.