rain on someone’s parade

rain on (one's) parade

To ruin one's plans or dampen one's excitement. I hate to rain on your parade, but I think your A in chemistry was actually a clerical error. Mom really rained on our parade by chaperoning our school dance.
See also: on, parade, rain
Farlex Dictionary of Idioms.

rain on someone’s parade

and rain on someone/something
in. to spoil something for someone. I hate to rain on your parade, but your plans are all wrong.
See also: on, parade, rain
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • at (one's) doorstep
  • at doorstep
  • at fingertips
  • at one's fingertips
  • at (one's) fingertips
  • at your fingertips
  • at somebody's expense
  • at someone's expense
  • at expense
  • at (one's) expense