(thing) by instantkarma Sat May 12 2001 at 0:52:22
  1. interjection. Used to express disappointment or sympathy. (a t-like sound produced by suction rather than plosion)

  2. noun. A brief, tight sucking noise made by suddenly releasing the tongue from the hard palate directly behind the front teeth, used to express disappointment or sympathy.

  3. informal. The sound I repeatedly made while reading your soft linked node.

Source: The American Heritage Dictionary of the English Language, Third Edition. Use permitted by applicable laws.
I like it!