2 Definitions:

1) A movie directed by Kevin Smith, a comedial genious.

2) A person who spends their time at the mall for no particular reason.

When you eat dirt for the first time and leave your family to build a shack in the woods

A hilarious Kevin Smith movie. It is one of the earlier Jay and Silent Bob films. The movie details a day two guys spend hanging out at the mall while trying to figure out a way to win back their girlfriends.

A surly teenager who spends all of his or her time at the mall with friends. Typically seen standing around glaring at customers -- sometimes these fascinating creatures will pick fights with mall security and call them "fascists" for enforcing the mall's loitering bylaws. Also often seen intimidating the elderly people in the clothing stores, they flock back to the "baggy pants with mile-long wallet-chain" section of the clothing store when an employee threatens to call the police.

One who goes to a mall with no shopping agenda
Mallrats usually know everything that's going around in the mall (I,e: when the Easter bunny stand comes up) and knows about everything about the mall (what stores going where how long a store has been there and what store was there before that store)
also a kick ass movie by Kevin Smith

Those for whom the Mall is a place of both recreation and relaxation, a place of worship and of desecration, and a place where one can happily pack a bagged lunch in order to spend all the time neccessary in order to see a stereogram image appear.

A person who frequently hangs out at shopping malls without actually shopping or working. Usually they are teenagers and sometimes young adults.