From what I know, it's when an 18-wheeler is carrying one of those loads, any loads, as
long as it's carry a load, and it's going at quite a highspeed, suddenly braking, causing the actual
truck itself to brake whilst the load's momentum behind the
truck forces itself in motion against the
truck, causing the load on the back to be intersecting at a perpendicular angle with the
truck. Look at this---> |_ The | is the actual
truck and the _ is it's load. The truck (|) is going forward, whilst the load (_) is scraping it's tires horizontally.
A jackknife is also responsible for causing many highway accidents, because when a truck jackknifes, it takes up all the lanes on the highways, and leaves no mercy for the vehicles in its path! Always speed up if you see a jackknife coming toward you if you cannot rapidly get off the highway.
*people driving*
Oh crap dude, that
truck is in the process of a jackknife, that
piece of shit volkswagon is in our way, guess the only choice we have is to speed up, step on it.
*person in volkswagon*
*ahhhh this is the life, *fart*,
beer and hot sauce...boomheadshot.*
