This expression describes someone who is very upset or agitated, but in America it might be taken to mean someone who is just plain fucking ugly as well.
He: "What's your problem this morning? You have a face like the devil's ass today."
She: "Yeah, and you would know...she is your mother, after all."
She: "Yeah, and you would know...she is your mother, after all."
by Captain Manic 59 March 1, 2011