A "napkin sketch" refers to a quick and rough drawing or illustration that is usually done on a napkin or any piece of paper. It is a simple way to express an idea or concept visually without too much detail. Full definition
This collaboration between director Mark Pellington (Arlington Road) and writer Alex Ross Perry (The Color Wheel, Listen Up Philip) unfortunately feels like cocktail - napkin sketch writ large (well, writ medium, anyway). (austinchronicle.com)