What's that in your pocket?

B came home with his jacket pockets bulging. I gave him the evil eye, thinking that he'd started collecting the schoolyard's nondescript rocks (read asphalt chips) again. "What's in your pockets?" I asked. B grinned mischievously and cracked both pockets open. "Poop." In spite of myself, I peeked. Sure enough both pockets overflowed with brown, gooey stuff. My face bunched into a disgusted expression. "Just kidding!" B laughed. "It's mud. But it sure looks like poop, doesn't it?"