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

Other days

first love

First Love Day
gum

Gum Day
law

Law Day
ormille

Ormille Day
youth

Youth Day
embarrass your best friend

Embarrass Your Best Friend Day
cursing

Cursing Day
boy friend

Boy Friend Day
prosecco

Prosecco Day
boba

Boba Day