rain on someone's parade
rain on (one's) parade
To ruin one's plans or temper 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.
rain on someone's paradeJOURNALISM
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.