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

Other days

cursing

Cursing Day
pampering

Pampering Day
kale

Kale Day
blanket fort

Blanket Fort Day
tulip

Tulip Day
cuddle up

Cuddle Up Day
singles

Singles Day
reading

Reading Day
artists

Artists Day
buddy

Buddy Day