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

Other days

pick me

Pick Me Day
tulip

Tulip Day
first love

First Love Day
self appreciation

Self Appreciation Day
lash

Lash Day
one

One Day
singles

Singles Day
nae nae

Nae Nae Day
kiss a ginger

Kiss A Ginger Day
promposal

Promposal Day