Oops, it doesn't look like 'stick up the ass day' is a national day..

Other days

bounce

Bounce Day
boyfriend

Boyfriend Day
lash

Lash Day
tulip

Tulip Day
latina equal pay

Latina Equal Pay Day
pumpkin

Pumpkin Day
bow tie

Bow Tie Day
ponytail

Ponytail Day
slime

Slime Day
gum

Gum Day