The act of a person committing suicide by jumping from the roof,
window, or balcony of a high-rise building.
The "Jam" is derived from the description of the person semi-
literally 'splattering' as they
hit the ground, while the "Mile" is derived from the long fall between the jumping spot and the ground.
Hotel Babylon quote: "It's much better if they
fly the Jam Mile. You know when they
jump off their balconies? It means we're not responsible for clearing up the
goo."