Whose poo?

"Okay, WHOSE POO IS IN THE BOWL?"

As Anthony and I went to see what all the fuss was about, Mark opened the door to the bathroom suddenly. "Somebody pooed in the toilet and didn't flush. WHO DID IT?"

All three of us denied being the excrementor in question, and a round of accusations commenced.

"I didn't do it, I just got home," Anthony said.

"It wasn't me, I haven't pooped all day," I said.

"Okay, listen: maybe somebody snuck in..." Mark began.

"And pooped in our toilet?" Anthony finished incredulously.

"Well, somebody did it," Mark insisted.

Later that evening, I caught Mark before he went to bed.

"Goodnight, Mark."

"'Night."

He walked into his darkened room, then abruptly turned around.

"Tim? You remember when there was the poo in the bowl and we didn't know whose it was?" Mark asked.

"Yes."

"Now that I think about it, I'm pretty sure it was me."