TP Slippage
When you cover a public toilet seat with TP, and turn around to sit down & your shorts/pants/dress knock that nice later of ass protection off the seat and into the water. Inevitably, you have to start over.
Man, I had to drop a deuce, but the seat was so nasty I had to use 3 well-placed layers of TP to protect my booty. I turned around to sit down, and there was massive TP slippage, and I had to start all over.