FM's are a commonly used slang for fake money
Ayo don't mix your FM's with your other bread or you fuck up and get bagged.
Full mana. Your mystical energies are fully available and you're ready to cast some spells.
Person 1: How are you doing on your mana levels, casters?
Caster: FM here, ready to sling some spells!
Fucking machine.
It's used in reference to a person who would you fuck repeatedly.
"Bro, that girl is such an FM, damn, wish I had a chance!"
an insult, when you mit is fabricated an or a glitch in the matrix
yoooo Jojo just pulled down his mask, he got a FM