Seconded. I've never heard this in the UK from people of any age.
I wonder if it has anything to do with the way "an" sounds when spoken with an American accent. A mishearing and then repetition of "an accident" seems much more plausible to me than confusion with "on purpose".
I wonder if it has anything to do with the way "an" sounds when spoken with an American accent. A mishearing and then repetition of "an accident" seems much more plausible to me than confusion with "on purpose".