I don't want to rain on your parade

What's that?  A present? 那是什么？礼物？

Diamond earrings. They're for Sue！钻石耳环。给苏的！

Wow！Uh...I don't want to rain on your parade, but Sue just got engaged. 哇哦！我不想给你浇冷水，不过Sue刚刚订婚了。

What？Engaged? She's gonna get married? What??? 什么？订婚？她要结婚了？有没有搞错？？？

rain on your parade是一个俚语，意思是扫兴，泼冷水。句子原意是在parade（游行）的时候下雨，可不是太扫兴了！