Shutter shades are a type of sunglasses that works by decreasing the amount of sunlight through a set of horizontal shutters (similar to a window shutter). rather than with tinted lens as with most other sunglasses. Shutter shades are made from a variety of materials, from chrome to plastic, and often come in many colors.
Shutter shades were a brief fad during the 1980s, but quickly died out. They are still pretty far outside the mainstream, but have recently gained in popularity thanks to their use by some well known rappers and hip hop artists.
Shutter shades should really be considered a type of novelty sunglasses or a form of peacocking, since they are completely outside the norm, and will stand out in pretty much any social setting. You can wear them ironically at a party to stand out and seem like a fun guy, and use them as a conversation piece. Alternatively, because of their popularity among rappers, you can also wear them as part of a more extreme & funky rapper outfit.