Faceplanted, fell, biffed, beefed, eaten shit. A person who has stacked has fully, bodily fallen all the way down, completely off of their
feet.
Always involves pain, usually accompanied by injury whether great or
small, to stack is to
hit the ground with your body, and without intention, so it necessarily hurts. A faceplant is always a stack, not every stack is a faceplant, thankfully.
This was common usage in skate culture in Northern
California Bay Area in the 1980s, still used frequently by surviving GenX of that area, we have passed it on to our children. Probably came about by watching our friends fly off of their skateboards perpendicular to the ground so when they hit, it stacked their body onto the asphalt or concrete. I can't believe this isn't already here.
Chris hella stacked grinding that rail, he
broke his clavicle and his nuts at the same
time, he'll be in the hospital a few more days, but we can visit.
**"grinding a rail" refers to a skateboard maneuver that involves sliding your board down a railing on the
deck- the part that is stood on to ride