descriptive noun
Describes a person who essentially ruins other people's fun, either because they openly disapprove of what other people are doing, or because their unpleasant attitude annoys or depresses everyone who would otherwise be enjoying themselves, if it weren't for that person acting like a 'wet blanket'.
The term is probably American in origin, first being used as slang in the mid 1800's. It was meant to compare a person to a wet blanket used to extinguish fires by smothering them, similar to how such a person would "extinguish" fun and excitement in social situations. Another, more modern
interpretation of the term likens a dislikable or overbearing person to the
aggravating,
uncomfortable feeling of being covered by a blanket when it's wet.
"William was at
the party last night and kept bumming
everyone out by
lecturing them about the 'dangers of alcohol and drugs'. Ha!"
"Yeah, that guy is such a wet blanket."