You know you've joked about it. One kid did it:
[Boy] tired of having his Mountain Dew stolen by a bully, filled the MD bottle in his backpack with urine and then watched in delight as the bully greedily helped himself to a big bottle.
Way to go, right?
Now the bully's family is threatening to sue. Over being a big dummy, I suppose? Just desserts had too much awesome sauce on top?