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

Other days

girl friend

Girl Friend Day
blanket fort

Blanket Fort Day
cuddle up

Cuddle Up Day
polyamory

Polyamory Day
youth

Youth Day
slime

Slime Day
one

One Day
get funky

Get Funky Day
buddy

Buddy Day
tell a fairytale

Tell A Fairytale Day