Oops, it doesn't look like 'sub ur ex day' is a national day..

Other days

get funky

Get Funky Day
cat girl

Cat Girl Day
one

One Day
brow

Brow Day
stud

Stud Day
bubble bath

Bubble Bath Day
promposal

Promposal Day
youth

Youth Day
unicorn

Unicorn Day
believe

Believe Day