The certain amount of size or area necessary for a tasteful tattoo. Varies due to size of person and placement on body. Anything larger than 6x6 inches goes past aforementioned area and becomes abuse of space.
Guy 1: Dude, check out this ribcage tattoo I got of a rib cage!
Guy 2: Whathorrible abuse of tattoo space. How much did that cost?
Guy 1: Whatever dude, it cost 200 bucks, but chicks dig tattoos.