As you see, we did use the potty. Sister was pretty puzzled by the whole thing but she played along nicely. And I received quite a lecture from the DH about statistics and probability and my method. I told him to be quiet- he was making my head hurt. Math is such a nasty thing. If I want to give away my prize in a statistically biased manner, I will. (But next time I'll use a random number generator like everyone else!)
And guess what... I WON SOMETHING! And yes, it was the CUPCAKE TOTE! I am beside myself. I never win cool stuff like this. So, thanks Jessica!