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

Other days

promposal

Promposal Day
law

Law Day
nae nae

Nae Nae Day
believe

Believe Day
ormille

Ormille Day
eat what you want

Eat What You Want Day
lisp

Lisp Day
donate your hair

Donate Your Hair Day
get funky

Get Funky Day
one

One Day