Similar to mall-core
. As a person: One generally in high school who frequents such stores as Hot Topic, revelling in their alt.life and thinking they're so alternative when they are simply doing the same thing that most other kids across the country are doing.
As a concept: Something that is trying to hard to be cutting edge and hip and cool but is about as edgy and cool as a warm bowl of oatmeal. "alt" for the masses.