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

Other days

promposal

Promposal Day
hannah

Hannah Day
aloxolt

Aloxolt Day
ruby

Ruby Day
fiancee

Fiancee Day
nae nae

Nae Nae Day
hiv awareness

Hiv Awareness Day
stress awareness

Stress Awareness Day
law

Law Day
reading

Reading Day