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a round, muscular buttock of prehistoric proportions; named after the Megaladon, a prehistoric marine creature known to have the most powerful bite in history.

a megladonk is said to be categorized better than a donk but less amazing than a sauroposeidonk; which is the classification of an amazing, plump epitome donk
Man 1: "Did you see girl over there?"

Man 2: "No.. (pauses to look...) OMG WTF WOW, that's a megaladonk.."
by royoroy May 12, 2012