Despite the name, Portside is definitely the right way to go, serving absolutely no port, but more than fifty varieties of rum, making it a slick Broadway Market speakeasy accessed through the loo (for real).
Head to cocktail bar Off Broadway, and go downstairs -- there, you'll see a cubicle with but a sink, and a cistern. Flush it, and the door will magically swing open, and no, they're not yanking your chain.
Inside, the feeling that you've descended into the belly of a colonial-era ship comes from gas lights on the walls, candles on the tables, and menus hidden in classic hardbacks. Don't steal them, that'd be a Moby-Dick move.
Start with caned-up classics like this rum Old Fashioned (served with super-dark chocolate on the side), or a kind of "rum Manhattan" known as a Sweet Palmetto.
Or go with their barrel-aged options, including this vermouth/Curacao-enhanced El Presidente. They'll be serving up booze-soaking charcuterie & light bites too, so you won't be the only thing that passes through the loo.