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.
boy #1 -dude, you just see a ghost?
boy #2 - no bro, i rode shotgun with Becky in the roadcoaster!
boy #1 - oh, shit..bathroom is down the hall, 1st door to your left!
Someone or something that bites your ankles.
To a postman, an ankle biter is often known as a dog.
To an adult, an ankle biter may be a toddler.
To hikers, an ankle biter is sometimes a tick.
And so on.