When a woman sits on the toilet backwards, a man then sits behind her. He places his erect penis flush against her anus as she begins to shit. As each turd is released and breaks off, the erect penis slaps back against the anus. This creates the distinct slapping sound of the Texas Mudflap.
"Thanks for the Texas Mudflap Hailee, my dick sure is shitty now," said Brett. "No problem, anytime," exclaimed Hailee.