Class Scavenger
One who is well known for consistently mooching food from his or her classmates, either in the cafeteria or at random, snack-friendly hours of the school day.

He or she also thrives on devouring leftovers, especially right before someone is about to throw away their crumbs.
Josh: Christ man.. Jimmy is such a fuckin' grade A Class Scavenger. Sometimes he eats more of my Totino Pizza Rolls than I do!!

Matt: Tell me about it man...