A load of mascerated shit held in a tank of a vessel. The load varies depending upon the size of the vessel. A recreational vessel will have a smaller shitload (20 G) than a commercial vessel (1000 G).
A large amount, so large in fact that it is riculous... like a load of shit would be riduculous (that is why the word is shitload and not something ordinary like people-load).
A colloquial term used to describe an extremely large quantity of something, often used informally to emphasize the overwhelming amount. Typically conveys a sense of exaggeration or intensity.