︎metric buttload n. a large but indeterminate quantity. Also metric ass-load, metric fuck-load, metric shit-load. (source: Double-Tongued Dictionary)
Further reading
Rosalind from Montgomery, Alabama, says her mother used to scold her for acting like a starnadle fool. The more common version of this term is starnated fool, a term that appears particular to Black English, and appears in the work of such writers...
In parts of Appalachia, the expression give someone down the road means “to reprimand” someone or “tell someone to get lost.” In Ireland, to give someone down the banks has a somewhat similar meaning, apparently referring to...
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/