One I always wanted to try but didn't have the balls to do: Go to school at midnight Friday night with several 50lb bags of salt - like what the northerners use for ice/snow. Salt the shape of a penis or boobs or the like in the front yard area of the school or on the football field. Make it big, big, big. In ~1 week all the grass in that area is dead. It's actually kinda difficult to get it to look normal again (grass seed will never grow), have to scoop up a few inches deep and throw it out then sod, etc. Kinda expensive, so don't get caught.
MS Paint for examples
Edit - ship monies to nswinger on stars, kthx.