the.com/spoilsport

The one who points out the fun has a flaw, usually correctly.

means Someone who ruins others' fun by refusing to join in or by pointing out why the fun shouldn't be happening.

from A straightforward compound from the late 1800s: 'spoil' plus 'sport,' sport here meaning fun or amusement in general, not athletics. One who spoils the sport — simple as that, no hidden twist.

origin
coined early 1900s, from spoil plus sport
cousin term
related to killjoy and wet blanket
irony
often right, which makes it worse
social role
enforces rules nobody wanted enforced
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