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

Other days

artists

Artists Day
bounce

Bounce Day
azonto is acceptable

Azonto Is Acceptable Day
my little pony

My Little Pony Day
gallery

Gallery Day
offer

Offer Day
stud

Stud Day
blanket fort

Blanket Fort Day
promposal

Promposal Day
bow tie

Bow Tie Day