A person who is an obsessive fan of the Toronto Maple Leafs hockey team. They are die hards who would drag their genitals through 5 miles of rosebushes just to touch the sweat stains of Dion Phaneuf's jersey. Very cocky and overestimate the actual talent of the Leafs.
Billy: OH SHIT THE LEAFS JUST SCORED WOOOOOOH! GO LEAFS GO! GO LEAFS GO! GO LEAFS GO! STANLEY CUP HERE WE COME!
, it's still the first round of the playoffs. You're such a beleafer.
Billy: Fuck you, Debbie.