A joey shack is a 3-sided, unattached shed roof structure added-on to the entrance of a trailer or house. When you pull the trailer out, the shack stays behind. Basically an extra storage room, a couple of sheets of plywood wide/long, for rain gear, canned goods, firewood, etc.
(Definition by Al Cool)
Ethan became anxious when a group of women rioted past the front windows of the trailer into the joey shack.