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

Other days

boba

Boba Day
gum

Gum Day
girl friend

Girl Friend Day
bubble bath

Bubble Bath Day
cat girl

Cat Girl Day
hoodie

Hoodie Day
ride the wind

Ride The Wind Day
unicorn

Unicorn Day
brow

Brow Day
ruby

Ruby Day