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

Other days

coffee

Coffee Day
girl friend

Girl Friend Day
comfy

Comfy Day
tell a fairytale

Tell A Fairytale Day
reading

Reading Day
ormille

Ormille Day
my little pony

My Little Pony Day
ruby

Ruby Day
aloxolt

Aloxolt Day
artists

Artists Day