it's on me
Ya sé que no es cosa mía pero come bien.
I know it's none of my business, but he eats well.
— Audition (2000)
Esto es cosa mía.
This is my thing.
El champagne es cosa mía.
Champagne is my thing.
— La dolce vita (1960)
Es cosa mía.
It's my thing.
— Anaconda (2025)
Eso es cosa mía.
That's my thing.