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

Other days

tulip

Tulip Day
blanket fort

Blanket Fort Day
bonang

Bonang Day
reading

Reading Day
boy friend

Boy Friend Day
ask out your crush

Ask Out Your Crush Day
singles

Singles Day
stud

Stud Day
boba

Boba Day
offer

Offer Day