'fse' is a phrase used when you just witnessed a funny moment, or watched a funny video.
It means: funniest
shit ever.
It is often used by teens
online.
It is a phrase too
awkward to say in real life though.
person 1 - "HAHHAHHAHAHA I"m
crying because that was so funny! I'm
dying of laughter"
person 2 - "dude, seriously? just
say fse. Because that was the fse."