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

Other days

lisp

Lisp Day
bow tie

Bow Tie Day
artists

Artists Day
azonto is acceptable

Azonto Is Acceptable Day
tulip

Tulip Day
cuddle up

Cuddle Up Day
offer

Offer Day
ponytail

Ponytail Day
bubble bath

Bubble Bath Day
boba

Boba Day