All Wallows’ Eve (n)

The night of boozy self-pity that follows the realization that one has, once again, failed to devise an original Halloween costume.
?In a sentence: “I can’t believe everyone at the party came dressed as Bella from Twilight as a sexy librarian. Oh, well—another All ?Wallows’ Eve, I guess.”

Related phenomena 11 o’clock New Year’s Eve datelessness; Christmas Eve charge-card rejection.