The story
Probably abbreviated from kiss my ass.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: Indicates disapproval, disagreement, or disbelief, often with a tone of disregard, disdain, or disgust, referring to the buttocks. Full definition →
Probably abbreviated from kiss my ass.
Etymology from Wiktionary, CC BY-SA 4.0.