After a long night of drinking and eating nothing but pizza and sausage biscuts on a car trip. One of the pasengers in the car emits a fart that smells so bad that all four windows of the car must be rolled down.
The amount of time you have to defecate after feeling the initial 'twinge' in your bowels. Length of allowable time varies drastically by person, and type of feces: Usually anywhere from 'right the fuck now' to 72 hours.
John: Ooh.
Alice: What?
John: I have to poop.
Alice: Ew, go ahead.
John: Not now, I just felt it, my shit window is usually 48 hours.