My-ass Definition

interjection

(slang, vulgar) Indicates disapproval, disagreement, or disbelief, often with a tone of disregard, disdain, or disgust.

She'll use my money to buy a new car, my ass!
You're his brother, my ass! You look nothing alike.
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pronoun

(slang, vulgar) I, myself; oneself in the third person.

My ass is tired.
Now I gotta drag my ass to work.
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