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

Other days

buddy

Buddy Day
aloxolt

Aloxolt Day
youth

Youth Day
carpenters

Carpenters Day
unicorn

Unicorn Day
mean girls

Mean Girls Day
boba

Boba Day
blanket fort

Blanket Fort Day
cat girl

Cat Girl Day
hoodie

Hoodie Day