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

Other days

camera

Camera Day
boba

Boba Day
cuddle up

Cuddle Up Day
ride the wind

Ride The Wind Day
me

Me Day
ponytail

Ponytail Day
self appreciation

Self Appreciation Day
martini

Martini Day
blanket fort

Blanket Fort Day
kale

Kale Day