I live in the midwest and, like some others, had never heard "on accident" until my son brought it home from school. He is very smart and gifted at language. But this drives me bananas. It seems to be a mistake -- yes, I agree with those who say it is incorrect -- that caught on and gained currency with this generation.

There are some other strange prepositional and article shifts among these teenagers as well, such as the deplorable "all of the sudden." What??? Kids here are all saying this, and my son, who was reading the newpaper and holding adult conversations at age 4 is now saying it. Appalling.