Oops, it doesn't look like 'show your tiny penis day' is a national day..

Other days

gum

Gum Day
boy friend

Boy Friend Day
frozen yogurt

Frozen Yogurt Day
nae nae

Nae Nae Day
youth

Youth Day
camera

Camera Day
cursing

Cursing Day
one

One Day
boba

Boba Day
ride the wind

Ride The Wind Day