A very large quantity in an unusual number or configuration (otherwise it would be an ordinary/English buttload). Compare: metric shitload and metric fuckton, which both designate a very large, but expected, quantity.
A most swag unit of measurement used by gangstas and pimps of a classier variety. Unlike its uncultured counterpart metric buttloads shitloads and fucktons are all base ten and as such far easyer to use in calculations.
On yesterday's evening I consumed a metric buttload of fine liquor. Unfortunately When I arose from my inebriated slumber, I found myself ducktaped to the underside of a freeway wearing nothing but my proud Union Jackskivvies.
