Used in an ironical sense to mean legitimate, and therefore, in reality, spurious and not at all legitimate. Assumes common knowledge of the inherent Simpsons reference.
Corpulent (Cor-pu-lent) simply means fat however it just makes you sound as if you have a bigger vocabulary and it will confuse and disorientate the person whilst you think up another insult.
Person 1: Wa gwan famalam?
Person 2: Suck out you corpulent wasteman.