Oops, it doesn't look like 'smack ass day' is a national day..

Other days

bow tie

Bow Tie Day
stress awareness

Stress Awareness Day
buddy

Buddy Day
eat what you want

Eat What You Want Day
my little pony

My Little Pony Day
gum

Gum Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
frozen yogurt

Frozen Yogurt Day
hannah

Hannah Day
bubble bath

Bubble Bath Day