I think it’s unlikely that it’s derived from U.S. slang. First, “ass” meaning “temper” is probably rare in the U.S., since I’ve never heard it. (And, of course, it’s never spelled “arse.”) Second, the term “can’t be arsed” meaning “can’t be bothered” isn’t used in the U.S. I think it’s more likely that there was an Irish (and British?) slang term “to arse” meaning something like “to bother” which arose separately. It probably happened that the Irish (and British?) meaning of “bother” for “arse” developed independently of the American meaning of “temper” for “ass.”
Simple explanation:
“Can’t be bothered getting of my arse and…” -> “Can’t be arsed…”
off, even.
Also in Dublin at least I occasionally hear the phrase “I couldn’t bother me arse”, which is even closer.
dylan beat me to it. As a Brit, that’d be my interpretation of the etymology of “can’t be arsed.”
As others have said, non-Brits hear the phrase and walla. 
No, no, no - it’s viola :rolleyes:
lol. Can’t slip an ironic joke past you 
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Here’s the original culprit defending herself.
I didn’t think too much when I wrote the phrase but I always thought there were two phrases, i.e. that you could say “arsed” and “asked”, one obviously a bit coarser than the other. I might have misheard it or garbled it myself. However, I could have sworn I have heard the “asked” version used which could well be possible judging from the Googled evidence. The resulting posts have convinced me it is actually wrong and I promise, hand on my heart, to never use it again though I suppose that if this keeps up after a while it will become neutralised as correct.
One more thing. It was NOT intended as a way of being overly polite. I have never been accused of that before. Flippin’ heck!
Thanks for bothering your arse to explain!
Warning: HijackArse
Apropos of the word Arse and US usage of it – are any European English speakers finding people using the expression “Jackarse” instead of “Jackass”?
To my ear it sounds like Her Maj. making reference to the wacky antics of Johnny Knoxville, Wee Man and Stevo.
Annoying pedantry aside – Jackass means Donkey yes?
So the show is Jackass regardless of which side of the ocean you view it?
No, it’s definitely still “Jackass”. We Brits differentiate between “ass” meaning donkey and “arse” meaning buttocks.
Of course, we have our own knock-off version of the show called Dirty Sanchez - and believe me when I tell you that you really don’t want to know the etymology behind that one.
Half-arsed - Only putting little effort into doing something.
Arse about - Messing about.
Get your arse in gear - Hurry up
Short-arse - Someone who is short.
Smart-arse - Someone who is smart.
Stupid arse - Someone who is stupid.
Why? I don’t know.
And of course nobody should forget arse biscuits!