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

Other days

tulip

Tulip Day
fiancee

Fiancee Day
get funky

Get Funky Day
ruby

Ruby Day
self appreciation

Self Appreciation Day
brow

Brow Day
pick me

Pick Me Day
book

Book Day
donate your hair

Donate Your Hair Day
hannah

Hannah Day