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.See also: on, parade, rain
rain on somone's parade
prevent someone from enjoying an occasion or event; spoil someone's plans. informal, chiefly North AmericanSee also: on, parade, rain