Something, or someone, that causes discomfort or is otherwise troublesome(noun)
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Use "pain in the ass" in a sentence
"Thirty years later, the “gaybies” what the good-humored offspring of baster-wielding lesbians and gays call themselves are all grown up, and are as huge a pain in the ass as the young adult offspring the rest of us had naturally."
"Even Trey wasn't a major pain in the ass anymore, his snotty attitude having downgraded tominor pain in the ass, with the occasional quip that actually had Daniel laughing the minute the kid left the room."
"Leading off the ninth, Brett Gardner, quickly becoming a pain in the ass to Angel fans all over, singled off reliever Matt Palmer."