A person who does not fit into a stereotype but wears a flatbill hat up and to the left no matter the occassion. Most closely resembles a guido but only listens to gangster rap songs you've never heard of. most J-Mass's are from south Florida around coral springs, but some may be found as far north as Jacksonville. A J-Mass may say "fire" or "that's f***ing straight" to refer to something cool. Their lives are fueled by the pursuit of sex and they will work harder for a woman than anything else. A J-Mass will also claim to have the biggest dick out of anyone in the room even though it won't be true. A J-Mass is a chain smoker, pothead, and will own atleast one bong. If a J-Mass wants to smoke with you he will ask by saying something along the lines of "ay bro, you wanna burn?"
Wow that kid on the skatebord with the flatbill hat over there is a real J-Mass.
"If you wanna step up to a monster cock just hit me up"