So for the past few months I’ve been telling my kids that, every time they write $(x+y)^2 = x^2+y^2$, they kill a puppy.  In fact, I will hereafter refer to that equation as the Dead Puppy Theorem, or DPT.  Since its discovery in early September, my students’ usage of the DPT has accounted for more canine deaths than heartworms.