The story
From the verbal expression spoil sport (“ruin the amusement”).
Etymology from Wiktionary, CC BY-SA 4.0.
spoilsport
Today it means: Someone who puts an end to others' fun, especially harmless fun. Full definition →
Today it means: Someone who puts an end to others' fun, especially harmless fun. Full definition →
From the verbal expression spoil sport (“ruin the amusement”).
Etymology from Wiktionary, CC BY-SA 4.0.