I've always wondered why people use the word "metric" in front of ton (or $hit-ton) in order to represent extreme emphasis.
While it's true that a metric ton represents more weight than a standard American ton, it's really only ~200 lbs more, which is only 10%. To me, that's not enough of a difference to warrant using it for extreme emphasis.
You could also say a "English long $hit-ton" because an English "long" ton is also roughly 200 lbs or 10% larger than an American "short" ton. But again, I don't feel that a mere 10% translates to extreme emphasis.