The appeal is that it's genuinely weird in a low-stakes way: a few hundred strangers in formalwear crammed into a BART car, which is either your idea of a great Saturday or it isn't. First-timers often underdress — go more formal than you think, not less. A cocktail dress or a suit reads as baseline; full gown or tuxedo reads as committed. Comfortable shoes matter because there's standing, stairs, and usually a walk to wherever the after-party lands.

Practical notes: Bring a Clipper card, not cash. The trains get crowded fast at the meet-up station; arrive early if you want to board with the main group. Bag your drinks — open containers are a citation on BART and will end your night early.

If you only have two hours, board at the starting station, ride one round-trip loop with the crowd, and skip the after-party. The train portion is the thing.