The term used to denote an ass that has undergone a certain amount of whipping, kicking, embarassment, or humiliation. Sometimes used as a derogatory for whoever owns said ass.
"Get your sorry ass out of here!"
Translation: I think little of you, so leave!
"I dragged my sorry ass out of there."
Translation: I felt like a moron, so I beat a hasty retreat.
"I pity your sorry ass."
Translation: I pity you, you worthless being.
Poor usage examples:
"I will make your ass sorry!"
"Your ass is so sorry that I laugh! Ha ha!"
"I have sorried your ass, it is now sorry."