Oops, it doesn't look like 'slap a yank day' is a national day..

Other days

buddy

Buddy Day
bubble bath

Bubble Bath Day
prosecco

Prosecco Day
lash

Lash Day
bow tie

Bow Tie Day
kale

Kale Day
ride the wind

Ride The Wind Day
singles

Singles Day
offer

Offer Day
latina equal pay

Latina Equal Pay Day