You know you want another potty story!

A couple of weeks ago, we were out in the back yard playing in the kiddie pools. Newly potty trained Greg was wearing a swimsuit with no swim diaper for the first time. All three kids were happily sliding and splashing, Jacob was alternately sleeping and fussing. I was on the phone with my brother.
Greg runs up to me, yelling "I need to go potty! I need to go potty!"
Well, we were outside, and Greg, being a boy, had already learned that he could pee outside. So, since I was on the phone and dealing with Jacob, I told him, "Just go in the grass."
Greg runs off, and I finish my phone call, happy that he was able to take care of things himself.
A couple minutes later, I notice Greg is still hanging around at the edge of the grass, and hasn't gotten back in the pool. I ask him  if he is ok, if he still has to go potty. Before he can answer, I notice the smell.
Yup, he did exactly what I told him. He went and stood in the grass and pooped in his pants.
So, I pull down his pants, and he sees what is there, and, in his most shocked voice, says "Oh! No!" As if he had no idea how it got there.
At that point, I did what any good mom would do on a 90+ degree day. I sprayed down my naked son with a garden hose and put him back in the pool.