You can wear a studded belt and listen to country, you can have a gold grill and listen to ska, you don't have to follow just one path. When you start dying your hair two-tone because everyone else at the concerts are doing it- you've become fashioncore.
When a band's videos are more important than their lyrics, they're fashioncore.
See also: poser
Tom: Looks like someone went fashioncore.
Dave: Did you see The Used on Making The Video last night?
Dave: That one guy kept bitching because he wasn't getting enough camera time.
Steve: How fashioncore.