spoilsport

Don't be such a spoilsport!

别让人扫兴！

牛津词典

Accuse me of being a spoilsport and I will plead guilty.

说我是个让人扫兴的人,我也承认.

期刊摘选

Don't be such a spoilsport!

别让人扫兴！

《牛津高阶英汉双解词典》