A trend-plague is any sort of trend that seems to be taking over the entire United States, but more specifically Corporate Media. We see it all day, every day. For example: Lil' Wayne, UGGS, vampire/werewolf movies, KiD CuDi, Wayfarer Sunglasses, Nsync, Disney Channel stars, Justin Beiber, Long boarding, The Jonas Brothers.
Basically, anything that is over played and owned by Corporate America and officially sucks. The trends that you see and hear every day that are soo irritating it feels more like a plague.