Used as an insult for any number of situations whereby it warrants that whatever is said is negated by a a directive that the other party would be better off if they were plucking the stank ass hairs out of your filthy gooch.
Teacher: Dan. Your scholastic performance is below par.
Dan: Pluck my gooch.
Boss: I need you to stay late tonight and help with clean up.
Employee: I need you to pluck my gooch.
Driver1: Hey asshole. You almost hit me.
Driver2: Pluck my gooch.