Means 'No, I don't agree' or just a general exclamation of many meanings - be it indifference, agreement or interest. Repeating it adds more value/feeling to the what you are trying to put across to your fellows. To be used with cautiously - people may think that you are weird if you do it too much.
'Isn't that a nice car?'
by Lizzy-Monster March 27, 2007