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

Other days

comfy

Comfy Day
believe

Believe Day
ponytail

Ponytail Day
ask out your crush

Ask Out Your Crush Day
lash

Lash Day
unicorn

Unicorn Day
slime

Slime Day
gum

Gum Day
tell a fairytale

Tell A Fairytale Day
artists

Artists Day