Idiom:  Party Pooper; used as a noun.

First Example:  

“All of us wanted to have a summer barbecue at the beach
this weekend, but when we mentioned our idea to Cindy, she immediately started
to complain about how hot the sun was and how much trouble it would be for us
to carry the food.  She is such a party pooper!”

Meaning:  A Party Pooper is a person who often
tries to reduce the interest or enthusiasm of others.  In this example, the majority of the group was
very enthusiastic about having a summer barbecue party at the beach.  However, Cindy did not share their excitement
over the idea and immediately started to complain about it.  The idiom, Party Pooper, is often used to describe someone who does not share
the same interest as the group and often tries to discourage them either
intentionally or unintentionally.  This
idiom can be used as a non-offensive way of describing someone who often
disturbs the fun of others.  The idiom is
most commonly used as a noun.

This idiom is from the book “Everyday Idioms for
Reference and Practice – Book One” which is used in the LSI Intermediate
Conversation Class.

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