rain on someone's parade, to

rain on someone's parade

 and rain on someone or something
Fig. to spoil something for someone. I hate to rain on your parade, but your plans are all wrong. She really rained on our plans.
See also: on, parade, rain
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

rain on someone's parade

JOURNALISM
If someone rains on your parade, they do something which spoils your plans or spoils an event that you hoped to enjoy. To make sure that all goes according to plan and no one rains on his parade, the president's safari will stay clear of trouble spots. It's irritating that he could rain on my parade by stealing the record before me.
See also: on, parade, rain
Collins COBUILD Idioms Dictionary, 3rd ed.

rain on someone's parade, to

To spoil someone’s plans or celebration. This term, which calls up a vivid image of a downpour spoiling elaborate floats and dampening spirits, has been around since about 1900. Sheila Rule, reporting on a plan to replace Britain’s House of Lords with an elected second chamber, wrote, “But the opposition Labor Party, which has long sought to rain on the Lords’ political parade, is once again aiming at those men and women” (New York Times, 1990).
See also: on, rain
The Dictionary of Clichés by Christine Ammer
See also:
  • lash down on
  • lash down on (someone or something)
  • drizzle down
  • conspire
  • conspire against (something or someone)
  • deter
  • deter (someone or something) from (something)
  • deter from
  • come under
  • come under (someone or something)