Oops, it doesn't look like 'best friend grabs my ass day' is a national day..

Other days

pumpkin

Pumpkin Day
kiss a brunette

Kiss A Brunette Day
brow

Brow Day
first love

First Love Day
gum

Gum Day
boba

Boba Day
blanket fort

Blanket Fort Day
hoodie

Hoodie Day
offer

Offer Day
lash

Lash Day