Rain On One's Parade Meaning

(idiomatic) To spoil someone's celebration.

Example: 2012 Jan 31, “Shah Rukh Khan, Shirish Kunder's drama ends”, Times of India, Bollywood:
  Sanju Baba, we learn, is rather miffed at the way Kunder rained on his parade and took away the spotlight from Agneepath's success.
2012 February 22, “European Stocks Fall on Worse-Than-Expected PMI Data; TUI Drops”, Bloomberg Business Week:
  â€œGiven that Europe is still shrouded by the cloud of recession, a weak PMI -- though not rain on the parade -- will surely damp investor sentiment,” said Manish Singh, the London-based head of investment at Crossbridge Capital