its basically a new word that ppl start to use in discord (not a lot of them) and this word is actually in French: FTTGGDMPC means "FERME TA TRÈS GROSSE GUEULE DE MERDE PETIT CANARD". To be honest, we mostly use it when someone annoys us, when we are trying to fight someone or when you troll somebody...
Acronym meaning "This made me laugh hard," usually used in an ironic fashion, in response to a lame post or unfunny meme.