What it means
A killjoy is the person who walks into a good moment and lets the air out of it. They don't have to be evil or dramatic, they're just weirdly talented at dropping the one comment that turns a buzzing room into a flat tyre. Handy for that mate who answers excitement with a warning, a complaint, or a miserable little reality check nobody asked for.
Usage examples
"I finally beat the boss, man, and Jake goes yeah cool, now do the nightmare mode. Dude is such a killjoy, I almost muted him."
"Do not be such a killjoy, one more song and then we will go home."
"He played the killjoy all night, moaning that the music was too loud."
"We were halfway into the pregame and Liv started banging on about train delays and hydration. Absolute killjoy behavior."
"Every group chat has one killjoy who replies to free drinks with yeah but it'll be rammed."
Where it comes from
Killjoy has been in English since the late 1700s. It's a straight compound of kill and joy, built to sound blunt and a bit rude on purpose. The word stuck because the picture lands fast. This is the person who doesn't just miss the fun, they stamp on it.
Other ways to say it
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