A phrase used to tell another person to politely say, "I have no interest in continuing this conversation or listening to you complain." In its hardly ever used long form, it would be used as, "I don't know what to tell you to get you to shut up." Extensively used when people present you with a problem, you offer advice to them on viable solutions, but they come up with excuses why they can't follow your advice.
Person A; "complain, complain, complain. My car broke and I can't get to work now. And boss says he'll fire me if I miss another day!"
Person B; "Take the bus."
Person A; "There's no bus route within a quarter mile, and my feet hurt so much."
Person B; "Take a cab."
Person A; "I can't afford a cab with these car repair bills!"
Person B; "I don't know what to tell you."