Potty training.
Nathan appears to be potty trained. At his age (almost 4) it was pretty easy... It cost me 3 M&M's per peepee and 6 M&M's per poopoo.. The key phrase that sealed the deal is "You get to pick them out"
Once he agreed to the deal, he has only had one accident, and went poopoo for the first time without any encouragement or fanfare at all..
On a side note, the flu is rampaging through our family. I am the only one who has not had the full onslaught. I still feel a bit buggy, so it may come at any time. Nathan puked all over the Walmart today. Good times...