Atypically run-down, low-rent houses found along the shores of small lakes. The term may also be used to insult residents of said houses. Lake goo is essentially trailer trash with a pontoon boat.
Jerry: "This sure is a pretty lake. But what's with the string of hillbilly huts?"
Bobby: "Where you've got lakes, you've got goo."
Jerry: "Lake goo? Let's get the hell out of here."