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

Other days

one

One Day
offer

Offer Day
gum

Gum Day
lost sock memorial

Lost Sock Memorial Day
bow tie

Bow Tie Day
pumpkin

Pumpkin Day
nail polish

Nail Polish Day
lumpy rug

Lumpy Rug Day
slime

Slime Day
kiss a brunette

Kiss A Brunette Day