rat line n. a covert path or itinerary used for smuggling, escape, or supply. Etymological Note: This term derives from the tendency of rats to create routes that are out of sight as much as possible, following perimeters and the bases of obstructions. (source: Double-Tongued Dictionary)
Further reading
Understanding the varieties of conversational styles can mean the difference between feeling you’re understood and being insulted. “High-involvement” speakers interrupt or talk along with someone else to signal their enthusiasm...