Oops, it doesn't look like 'No Best Friend day' is a national day..

Other days

bow tie

Bow Tie Day
boy friend

Boy Friend Day
cat girl

Cat Girl Day
self appreciation

Self Appreciation Day
me

Me Day
polyamory

Polyamory Day
promposal

Promposal Day
self care

Self Care Day
embarrass your best friend

Embarrass Your Best Friend Day
stud

Stud Day