A person who passes you on the highway going at least 20mph over the speed limit, thereby nearly ensuring that any cops ahead of you will be well occupied by the time you get there.
Passenger: Aren't you worried about getting a ticket? You have the cruise set on 80! Driver: No sweat! Didn't you see that hog chow pass us doing 90 a mile back?
(normally another word is inserted between "a" and "chow", ie. fucking, stupid, dirty, etc... feel free to insert more than one word, to mix it up, if you like!)
(Also, it doesn't always have to be used in a bad way)