Hit the Buick
Derived from "Hit the Wall". Getting stuck behind a slow driver after cruising along smoothly. Usually occurs on a two-lane highway in good weather after a long stretch of empty road and is caused by an elderly driver in a Buick (because that's what they buy) going below the posted speed limit.
We were cruisin' nicely on Highway 138 until we hit the Buick and there was no place to pass him.