A messy situation; an example of sloppy handiwork; a consequence of poor planning; a gathering that has descended into debauchery and chaos
"Dude, you're about to head out on a river trip and you haven't packed a lifejacket or nearly enough beer. You're runnin' a junkshow!"
Or, "The trip was a complete junkshow. By the second day we had gotten into the hard liquor, and by the third day everyone was dancing on the tabletops."