Oops, it doesn't look like 'wear ur lilly day' is a national day..

Other days

youth

Youth Day
nail polish

Nail Polish Day
offer

Offer Day
girl friend

Girl Friend Day
donate your hair

Donate Your Hair Day
artists

Artists Day
fiancee

Fiancee Day
prosecco

Prosecco Day
cursing

Cursing Day
bounce

Bounce Day