dingdong /(?)/

ding·dong

dingdong

n.
  1. The sound of, or as of, repeated strokes on a metallic body, as a bell; a repeated and monotonous sound.
  2. An attachment to a clock by which the quarter hours are struck upon bells of different tones. (Horol.)
  3. a stupid or foolish person; -- used in a deprecatory or contemptuous sense. [slang]