Hash browns. From the slurred pronunciation, by drunk punk boys in Seattle's University District in the '80s, of the word "bags," meaning bags of potatoes, specifically Food Bank hash browns stockpiled in punk households.
"We still'ave those jjjags... ofp'... tatoes o'er... ere."
-attributed to Sergio
"You'll be eating jags at Beth's on Aurora"
(from <i>Frozen Beer in the Microwave</i> by 13 Helicopters)