doesn't matter at all
Me importa un comino estar a la moda.
I couldn't care less about being fashionable.
— La vida de Adèle (2013)
¡Oh, pareces haberme confundido con alguien a quien le importa un comino!
Oh, you seem to have mistaken me for someone who gives a damn!
Me importa un comino si Tom viene o no.
I couldn't care less whether Tom comes or not.
I couldn't care less.