Oops, it doesn't look like 'pet best friend day' is a national day..

Other days

slime

Slime Day
boyfriend

Boyfriend Day
ormille

Ormille Day
lisp

Lisp Day
tulip

Tulip Day
my little pony

My Little Pony Day
book

Book Day
one

One Day
eat what you want

Eat What You Want Day
singles

Singles Day