This phenomenon occurs when one is in the process of defecating. In order to occur, the fecal flux must be a single, uninterrupted outflow, creating a log of such magnitude that the stool reaches the bottom of the bowl before being released. Once this delicate equilibrium is broken, the crap proceeds to fall forwards, gently tickling the underside of your testicular sac, leaving a brown deposit in its wake. This rare occurrence is known as the "brown bag".
-dude, your toilet bowl is so shallow, it gives me brown bags all the time!!
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