Eating 1000s of Big n Beefies with Fries at Drill Finger's Fortress
His own weight
Big Fat Jeffy, Retard, Mario 2.0, Dumb Fatso, Master Jeff, (by some Teletubbies)
Drill Finger, The Toddler, Teletubbies, Henry and Samantha, SMG3, SMG3's allies, Being fat, Committing petty crimes, Robbing banks, Thinking his the most dangerous villain, Every Fast Food Restaurant, Big 'n' Beefies (a type of big large burger), Fries, Coke, Grape Juice, Battles, Chocolate Cake, Any cake, Cookies, Cupcakes, Resting in Drill Finger's Fortress or any of it's neighbouring bases, etc.
Mario, Luigi, SMG4, Woody, Bowser, Bowser Jr., Protagonists, His crimes being derailed, Being knocked over (because his weight makes it almost impossible for him to get back up), etc.
Jeff is a very fat and dumb villain and an enemy of SMG4 (almost as dumb as Mario). He is an ally of the Toddler and due to his intelligence he is NEVER the main antagonist of any Longplay. He loves eating large burgers with fries. He's very strong but not powerful enough to beat Mario and SMG4. He just keeps appearing however.