“Je m’en fiche” is a familiar expression that means “I don’ t care”…
But you will often hear people say “Je m’en fous” which is even more familiar than “Je m’en fiche” but used quite a lot in a conversation.
Note: As you can hear, we don’t often pronounce “e” of “je” in spoken french because we speak quite fast so we say /j’men fish/ & /j’men fou/…So, now it’s your turn to say these expressions as many times as you want & try to imitate my pronunciation as closely as you can!