In alpine skiing, being in a position where one's center-of-mass is shifted toward the tails of the skis instead of toward the tips. Results in reduced control, adaptability to changing terrain, and ability to make a full turn.
I hit that rut hard and got thrown into the back seat.
Backseat is when something is horrible and sucky. This makes perfect sense because no one likes to sit in the backseat, and sometimes nasty things happen in backseats. This will catch on in the near future.