Trucker's Butt is a condition where your ass is slightly sore after sitting on it for a long duration of time while on the road. It is typical during long road trips, especially on trips that are more than 450+ Miles.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.