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

Other days

hot chocolate

Hot Chocolate Day
pampering

Pampering Day
singles

Singles Day
stud

Stud Day
special education

Special Education Day
cuddle up

Cuddle Up Day
unicorn

Unicorn Day
bow tie

Bow Tie Day
bounce

Bounce Day
gum

Gum Day