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

Other days

gum

Gum Day
cuddle up

Cuddle Up Day
first love

First Love Day
martini

Martini Day
donate your hair

Donate Your Hair Day
kiss a ginger

Kiss A Ginger Day
comfy

Comfy Day
buddy

Buddy Day
boy friend

Boy Friend Day
promposal

Promposal Day