metric buttload n. a large but indeterminate quantity. Also metric ass-load, metric fuck-load, metric shit-load. (source: Double-Tongued Dictionary)
Further reading
Language is always evolving, and that’s also true for American Sign Language. A century ago, the sign for “telephone” was one fist below your mouth and the other at your ear, as if you’re holding an old-fashioned candlestick...
Brittany in Green Coast Springs, Florida, says that when she was grumpy or irritated as a child, her mother would say a phrase that sounded like Don’t be such a scooch. This bit of Italian-American slang, often rendered as skutch, denotes a “pest”...
I don’t know if you care about etymology, but it seems to be derived by analogy to ‘metric ton’ (1 Mg or 1000 Kg), which is about 10% larger than the ‘short ton’ of 2000 lbs. commonly referred to as ‘ton’ in the US. Therefore, a ‘metric assload’ would be even larger than a normal assload.
I read about this in “the Writer” and just had to respond. I ended up writing a blog about it. http://logikalblog.com/2009/11/17/metric-buttload/