What it was like
Every other holiday asks you to dress up nicely. This one asks you to dress up as somebody else entirely — masks, costumes, the whole story turning on the fact that identity gets scrambled for a day. Which makes the comic book crossover far less of a gimmick than it first sounds.
So the costume contest here contains multitudes: a kid dressed as Queen Esther standing next to a kid in a superhero cape, and both of them are exactly correct. There are family activities, holiday-themed entertainment, groggers going off at the right moments, and the specific joy of grown adults who committed way too hard to a bit.
It happens at Chabad of Santa Monica, on 17th Street.
Bring the kids and let them pick the costume without editorial input. That is the tradition, and you were never going to win that argument anyway.