A very straightforward phrase describing a feeling of apathy and denial towards another person's thoughts or ideas. Although mostly used to express one's lack of care for some sort of argument, it occasionally is a literal command. In addition, it is one of the worst possible comebacks in the English language.
Gay Person: "Yo, I got 'x=3' for question 5."
Normal Person: "Dude, that's wrong. It equals 2."
Gay Person: "Suck my dick."
Normal Person: "I would rather not."
Person 1: "Hey, wanna suck my dick?"
Person 2: "...Jennifer, I think we should break up now."