The Incredible Parker was Parker's alter-ego and a monsterific version of himself.
In "The Incredible Jerk," Parker was unbother of all of the insults but the years of doing so take a told on him, and then, he turned into Incredible Parker and went on an insulting rampage. Josh manage convince Parker to let his feels out. In the end, Parker is normal and everyone apologizes to Parker for insulting him earlier, but back at Mr. Meaty, Josh sees some heavy boxes in the freezer, and gets Parker mad so he could move them out. However, when Josh tells Incredible Parker that he needs him to lift the boxes out of the freezer, Incredible Parker responds, "No! How 'bout you clean yourself?!".