throw a wet blanket over something

throw a wet blanket over (something)

To make something be or seem less enjoyable, successful, or important. The court's decision throws a wet blanket over the president's plans for healthcare reform. Her crappy attitude really threw a wet blanket over the party. I could tell that Sean's football victory threw a wet blanket over Sam's news about getting into the college she wanted.
See also: blanket, over, throw, wet
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

throw a wet blanket over something

AMERICAN
If something throws a wet blanket over an event or situation, it makes it less successful or enjoyable. Cool, rainy weather has thrown a wet blanket over Michigan's tourism season.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
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