Oops, it doesn't look like 'bffffffs day' is a national day..

Other days

polyamory

Polyamory Day
tell a fairytale

Tell A Fairytale Day
bow tie

Bow Tie Day
lisp

Lisp Day
promposal

Promposal Day
boba

Boba Day
tulip

Tulip Day
law

Law Day
pampering

Pampering Day
ride the wind

Ride The Wind Day