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

Other days

bow tie

Bow Tie Day
gum

Gum Day
tulip

Tulip Day
martini

Martini Day
azonto is acceptable

Azonto Is Acceptable Day
lisp

Lisp Day
self care

Self Care Day
youth

Youth Day
hoodie

Hoodie Day
cuddle up

Cuddle Up Day