Mullet; a haircut short on the sides, but long in the back
Half of the guys at the Poison concert had mullets.
The haircut now chiefly known as a "mullet", although the term "schaum" predated it by several years. Can be used with various prefixes: feather-schaum, mexi-schaum, etc. Origin of the word: it's a shortening of "a Schaumberg", which is a direct reference to the city of Schaumberg Illinois, where such a haircut was predominant in the early 90's.
Check out the mexi-schaum on that guy!