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

Other days

hannah

Hannah Day
nail polish

Nail Polish Day
lumpy rug

Lumpy Rug Day
azonto is acceptable

Azonto Is Acceptable Day
kale

Kale Day
cursing

Cursing Day
prosecco

Prosecco Day
blanket fort

Blanket Fort Day
ruby

Ruby Day
gum

Gum Day