My almost five year-old son walks up to me this morning while I'm on the john holding what looks like a crushed chocolate Mentos or hard candy of some sort. Groggily I'm like, "What's that?" Now the fact that I just saw him take his hand out of his pants should have aided me in putting two and two together, but I had just woken up, and it didn't look like anything bad, so I put my hand out and say, "Give me that," and it felt hard like candy but at closer inspection it certainly was not.
I asked him if he remembered going to the bathroom in his pants and he said no. I checked the underpants he slept in, and the one's he had just put on and they both showed no sign of being soiled, so it was like the mystery Mentos poop fairy dropped off a gift in his tighty-whiteys.

I know I often post the grosser aspects of being a parent, but I guess it is because, though I've come to accept it, being intimate with other people's bodily functions and their resulting materials is something so different from my experiences before I was a parent, that they seem somewhat surreal to me.