A person or thing that spoils a good time or ruins a good mood.
Use: Jo and Kendra are discussing an upcoming event...
Jo: Kendra, are you going to invite Lisa to your birthday?
Kendra: I would like to, but do you remember the last time we were all together? She wouldn't stop talking about how angry her boyfriend made her.
Jo: True. She was a real party pooper. We were having a great time until she arrived.
In the example, Jo and Kendra talk about how they were having until Lisa arrived. In other words, Lisa's complaining about her boyfriend killed their fun. That is why Lisa is a party pooper.
-- Iain McConnell, APC Language Systems #DTLA
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