Definition
A denial to proceed a ruling out of any possibility.
How People Actually Use It
The moment just prior to having uncontrollable diarrhoea. A red light gives you approximately 10 seconds to make it to the bathroom before wherever you are becomes ground zero for a "pooclear" explosion.
"I was on the train to work this morning when without warning I got a red light and some fucker was in the bathroom! I had no choice but to go in the sink!"
Source: Urban Dictionary