Generally used in hyperbole.
Note: proper usage demands the British spelling of "tonne" becuse the extra letters are also absurd.
1 Imperial Fuckton = 1.016 Metric Fucktonnes
"That's nothing faeg, I've a metric fucktonne of assignments due tomorrow morning"
"So, still going on the beer tonight?"
"Does the Pope shit in the woods?"
Built upon the Old English term "shit load", which is very lacking in actual measurable significance, a Metric Fuck Tonne is a significantly more accurate. Easily identified with the abbreviation FT, a Metric Fuck Tonne is greater than one may care to measure. Most commonly used to describe weight which is clearly no less than one thousand kilograms, but when actual measurement has not taken place. Not to be confused with the antiquated, Imperial Fuck Tonne.
Frank: "Was that a imperial fuck tonne James?"
James: "Great question Frank - It was definitely one Metric Fuck Tonne"