Someone who is constantly complaining or picking a fight over perceived injustices.
I first saw this usage in a Sports Illustrated article about the baseball manager Lou Pinella. In the article Pinella, who is notoriously bad about arguing with umpires, referred to himself as a red ass. I liked the term so well, and it applied to some in my family, it was entered in to the family lexicon.
Dude1: "I got some serious fucking red ass!"
Dude2: "What's up?"
Dude1: "My boss just told me I have to work the next ten days straight, or I'm fired."
Having digestive issues and wiping very frequently, the Red Ass gets a very sore and irritated burn around the anus area that usually includes the scrotum. The Red Ass has high stress and bad diet, and is usually chemically dependent. It becomes a never ending condition, giving them a warped attitude from the constant pain and the mental illness. This devolves into an obsessed, resentful, hatred of all mankind. This resentment seeths and permeates everything the Red Ass does. Beware because they are out for revenge and reactionary.
That Red Ass got another Shit Stain and laid a rope across the road and then they pulled it up to knock Robert off of his motorcycle as he ripped by.