FYB means Follow Your Bliss. The connection between happiness and bliss is this: Bliss is the pathway to happiness. Happiness is a state of mind; following your bliss is how you get there.
FYB is a popular term among(us) youths that is an acronym for 'Fucking Your Bitch' or 'Fucking Yo Bitch'
It is particularlyhilarious to troll someone's Sendit on Snapchat by spamming it with confusing or funny things and including 'fyb' in each one.
Gym bro: Hey broski do you lift? Like...are you getting them gains yk🥶
Fully lit bro: Nah dude I'm way too busy FYB
Gym bro: OHH DUDE THAT WAS A FULLY SICK AS ROAST. MADE RESPECT FR THAT WAS SAVAGE.