A phrase used to reference an object/person/event in a way that appears to be "out of date". It is a polite way to tell someone there music/hair/car/wardrobe/home electronics/home furnishings are TERRIBLE and they need new ones!
Glenn: Dude,look at that chick over by the bar,she is HOT!
Longo: DUDE, look at her hair, she is "Real 80s" man. Those jeans she has on, in San Diego you never see that style, that's "Real 80s".