The ultimate answer to any statement, showing that you think that what's been said is a load of bollocks, or at least that the other person doesn't deserve a reply that takes any of your valuable brainpower. If the other person is playing along, they should come back with a perfectly-weighted "Well..." with accompanying gestures.
"Britney Spears' latest album is the greatest piece of music of our age."
"Is it though?"
"I roxor your socks."
"Do you though?"