Something a person will say when they don't care what a person has to say. Phrase is most heavily used by people who are being talked to by a liberal or polititian. The phrase can be tracked as far as the year 1812s when the English told Americans that they are mean and need to give them thier land back. The Americans replied "I dont give a shit".
I don't you fully appreciate on how mass of a scale I dont give a shit.