An Unbirthday is described as an event that is typically celebrated on any of the 364 or 365 days in which it is not the person's birthday. It is a neologism coined in Lewis Carroll's Through the Looking Glass, giving rise to "The Unbirthday Song" in the 1951 Disney animated film Alice in Wonderland. en.wikipedia.org/wiki/Unbirthdayhttp://en.wikipedia.org/wiki/Unbirthday