U.S. Army Airborne slang for the phenomenon in which
one has to shit so badly it could blow at any moment.
Having 'Jumpers in the
door' is an emergency situation usually characterized by a frantic race to the
toilet, and in which if a bathroom facility is not located immediately a huge mess in
one's underwear could occur.
The actual phrase is coined after a chalk of U.S. Army paratroopers awaiting the green light during an Airborne operation, so they may exit the aircraft -- particularly the number 1 jumper who is waiting directly in front of the
door for the light to change.
The civilian equivalent of this expression are, Turtlehead poking our, or TTF - Turd Touching Fabric
Dude #1, "Hey
man, why are you walking like that?
Where are you going in such a hurry??"
Dude #2, "Can't talk right now bro, got Jumpers in the
door.."