Used to describe someone or something that is a complete and utter mess. A big fat mistake and everybody knows it. A complete waste. Someone who is so weak that it's laughable
Friend 1: I spent all last night playing Fortnite instead of studying for the midterm. Why am I such a jeb?
Friend 2: a BIG. fat. jeb. For once I wasn't a jeb and actually studied. Repent from your jebbish ways or else your GPA is gonna be a jeb too
(Other forms include: jebbing, jebbish, jebbishly )