To be extremely muscular to the point of resembling a hairless, large primate. Gorilla jacked specimens can expect to have bulging veins, shaved heads, and, in rare cases, muscles on top of other muscles. Incorrect form during exercise can lead to extreme cases of being gorilla jacked, in which one literally walks on their knuckles and feet.
Rick: "Dude, look at that guy benching over there!"
Jake: "Oh shit son, he's getting gorilla jacked for sure!"
Anne: "Ew, why is he walking like that?"
Jerry: "Oh, he must have gotten too gorilla jacked."