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

Other days

law

Law Day
frozen yogurt

Frozen Yogurt Day
ruby

Ruby Day
emoji

Emoji Day
bow tie

Bow Tie Day
tell a fairytale

Tell A Fairytale Day
nae nae

Nae Nae Day
offer

Offer Day
aloxolt

Aloxolt Day
ride the wind

Ride The Wind Day