A present that unfortunate kids like me must get when you want something that the family can only afford if you combine your birthday present money with your Christmas present money. Thus, you don't get anything for one of those holidays.
A state of mind frequently experienced in the days leading up to and immediately following one's birthday, characterized by confusion, euphoria, irrational behavior, and severe hangovers.
The period from about December 20th - January 5th in which a person's birthday may fall and they get a "Christmas/Birthday Present". I.E. They get one present for their birthday and Christmas instead of two due to their birthday falling so close to the holiday.
An annual event that celebrates the fact that your wedding anniversary and birthday are on the same day. You can then say "Happy Birthsary" to celebrate both with the efficiency of one.