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

Other days

promposal

Promposal Day
pick me

Pick Me Day
boba

Boba Day
ormille

Ormille Day
unicorn

Unicorn Day
chocolate milkshake

Chocolate Milkshake Day
ruby

Ruby Day
self appreciation

Self Appreciation Day
cursing

Cursing Day
cuddle up

Cuddle Up Day