flag day

Noun

 * 1)  A day on which a registered charity raises money, usually by selling small lapel flags.
 * 2)  A day on which a registered charity raises money, usually by selling small stickers.
 * 3)  A day designated for changing to an incompatible system.
 * 4)  A change which is neither forward nor backward compatible.

Translations

 * Finnish: keräyspäivä