when riding shotgun with somebody, who, just for a split second, takes their eyes off the road, looks back and realizes they drifted 2 feet out of their lane and proceeds to jerk the car back in to position so violently that your neck suffers whiplash. just like riding a rollercoaster, it can also be done in smaller jerks that, by the end of your ride makes you look for the first bush to purge behind.

When you eat dirt for the first time and leave your family to build a shack in the woods