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

Other days

aloxolt

Aloxolt Day
bounce

Bounce Day
lash

Lash Day
singles

Singles Day
girl friend

Girl Friend Day
self appreciation

Self Appreciation Day
stud

Stud Day
brow

Brow Day
ormille

Ormille Day
blanket fort

Blanket Fort Day