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

Other days

book

Book Day
buddy

Buddy Day
ponytail

Ponytail Day
blanket fort

Blanket Fort Day
gum

Gum Day
nae nae

Nae Nae Day
slime

Slime Day
pumpkin

Pumpkin Day
boy friend

Boy Friend Day
lumpy rug

Lumpy Rug Day