Hate to burst your bubble, but calling someone an "ass" is a reference to donkeys, aka asses, which are stubborn, obnoxious creatures.
The correct spelling for that animal name is "ass," not "arse." Thus, the correct spelling for the pejorative is also "ass."
(and now you know why my friends call me Grammar Girl. Some times they say it like that's a bad thing? )
But I completely agree that the metric system is far superior to the Imperial; wish the US had switched way back when. I'd even be willing to go through the pain to switch now.
Haha, I was going to mention "ass" as in donkey. But, I'd argue that the etymology of our colloquium "arse" is older. The roots are Germanic. Originally it was a polite way of saying bum, but, by time king Henry VIII was around, it was used colloquially. It was only around the 19th century, that the American "ass" emerged.
Interestingly, we pronounce ass (as in the animal) to rhyme with ‘mass’, and arse to rhyme with ‘farce’.
There'd be some who'd argue they are interchangeable, but only to a point, in my opinion.
We don't use it colloquially to mean donkey, but rather, the human or animal posterior. As in, "you are the donkey's arse"
I had an etymology obsession for a while, absolutely love looking at where words came from.
I know this is completely off topic. I apologise
haha, great minds, we were obviously typing at the same time