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

Other days

slime

Slime Day
bounce

Bounce Day
boy friend

Boy Friend Day
girl friend

Girl Friend Day
ride the wind

Ride The Wind Day
prosecco

Prosecco Day
lumpy rug

Lumpy Rug Day
ormille

Ormille Day
believe

Believe Day
cuddle up

Cuddle Up Day