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

Other days

bonang

Bonang Day
pick me

Pick Me Day
hoodie

Hoodie Day
boba

Boba Day
embarrass your best friend

Embarrass Your Best Friend Day
lisp

Lisp Day
boy friend

Boy Friend Day
first love

First Love Day
ormille

Ormille Day
stud

Stud Day