Oops, it doesn't look like 'pet siblings go fuck yourself day' is a national day..

Other days

promposal

Promposal Day

book

Book Day

carpenters

Carpenters Day

cuddle up

Cuddle Up Day

Emoji Day

hiv awareness

Hiv Awareness Day

gallery

Gallery Day

tell a fairytale

Tell A Fairytale Day

china

China Day

tell ur crush you like them

Tell Ur Crush You Like Them Day