HKH was an android designed to fight to Hulk his power set makes him invulnerable to blunt force and Hulk's who repertoire of physical powers. Some idiot (I forget who) claims it as the the most powerful creature in comics because it did so well against the Hulk. The joke is that, while powerful, it could easily be killed with a nail-gun or a good battery.
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Graffiti outside Latin class.
Sed quis custodiet ipsos custodes?
A juvenal prank.