Had a conversation with my partner the other day, and I was quite convinced that the phrase originated in the south well before the time of the internet.
However the only references I can find of it on the internet refer to it's first use in 2010 on Funny Junk.
http://knowyourmeme.com/memes/that-really-rustled-my-jimmies
it might be worth x-posting to /r/etymology
Google Books has no hits from the twentieth century. What is the basis of your belief that it predates "the time of the internet"? Did you use it personally?