Oops, it doesn't look like 'Party In The Usa day' is a national day..

Other days

promposal

Promposal Day
ruby

Ruby Day
offer

Offer Day
pick me

Pick Me Day
cuddle up

Cuddle Up Day
stud

Stud Day
artists

Artists Day
unicorn

Unicorn Day
first love

First Love Day
my little pony

My Little Pony Day