wet blanket
US /wɛt ˈblæŋkɪt/
UK /wɛt ˈblæŋkɪt/

1.
扫兴的人, 泼冷水的人
a person who spoils other people's fun by being negative and unenthusiastic
:
•
Don't invite John to the party; he's such a wet blanket.
别邀请约翰参加派对;他真是个扫兴的人。
•
She's always being a wet blanket, complaining about everything.
她总是扫兴,抱怨一切。