Unbirthday

[Cami]

Any day except ones birthday.

[Dianne]

[Statistics] prove that you have one birthday, just one birthday every year. But there are three [hundred] and [sixty-four] unbirthdays. And this is a reason to gather and cheer.

[Little_Girl]

all [the days] besides [your birthday] in a year, referred to in [Alice in Wonderland] also

[Kit]

the day of a [siblings] [birthday] where you also receive [presents]/money in order to keep the peace.

[Ernesto]

When you [acknowledge] that it is, indeed, the date of [your birth], but refuse to acknowledge that you have [aged].

[PussyCat]

the opposite of [your birthday]; [the day] of your [future] death