Out-of-town travel for the primary purpose of visiting an automotive salvage yard on multiple consecutive days. Usually refers to self-serve or pick-a-part junkyards, where customer labor is required to procure purchases. On a typical junk-cation, you'll drive to the city with the awesome junkyard, spend the whole day pulling parts, crash at a motel, then come back the next day and do it again.
I'm going to Chilliwack this weekend and I think I'll make a junk-cation of it. There's just too much in that yard to do all in one day.