The act of taking a poop, in which you know you pooped, however, there is nothing in the toilet bowl to flush except the bum wipe.

to go into a freshly cleaned public restroom, dropping a fat deuce, not flushing, and exiting the restroom unidentified.

After performing the act of dropping a deuce, refers to the absence of leftover feces about the buttocks. Therefore, leaving nothing behind to wipe. It's a mystery.