To beat someone's ass so severely that without even fighting as hard as you can, there is no doubt that your opponent is severely outclassed. This term is most appropriate when administered by someone who is from a rural area, especially when it's given to a nancy pants city boy.
Bo & Luke found the man from Atlanta who groped Daisy and gave him a good old fashioned country ass whooping.
In the state championship football game, East Podunk HS gave City Boy HS a good old fashioned country ass whooping. The score was 63-0. After the first quarter. Then East Podunk put in their first string.
Phone conversation with:
Your mom- *sigh, I have nothing to do tonight. My kids are out of town and my husband, at work.
Me- Well, how bout I come over and we'll have some good old fashioned fun.
Your mom- ...Yes, I'm so horny.
Me- Say no more; I'll bring the lube. I like it nice and sloppy.
Your mom- Just like me.
Me- That's right, bitch.