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

Other days

first love

First Love Day
coffee

Coffee Day
polyamory

Polyamory Day
fiancee

Fiancee Day
book

Book Day
lumpy rug

Lumpy Rug Day
gum

Gum Day
lost sock memorial

Lost Sock Memorial Day
boy friend

Boy Friend Day
bow tie

Bow Tie Day