This’ll help you fight the post-Halloween depresh of having to put your Sexy Cthulhu costume back in the closet for another year: Saturday, the Museum of Sex hosted an outrageous new party that’ll give you an excuse to don your wildest S&M gear every Saturday — just keep in mind you’ll have to remove all sharp objects before entering the big-boob bounce house.

Musician Kayvon Zand, host of the Chic Freak parties at The Box and the Dorian Gray parties at The DL and now Bowery Electric, has teamed up with Brendan McElroy (yes, St. Marks’s own Dr. Brendan) for the new weekly, Sex on Fifth. These days, it’s rare that you get four floors to club in — much less floors outfitted with phallic climbing walls and mirror mazes that invite you to “find the G spot.” But during Saturday’s launch party, the Museum of Sex reminded us of an amped up version of Mistress Formika’s bygone venue, Speed — which, come to think of it, was probably the last time we partied like this in midtown.

On the fourth floor, strapping drag queens competed in an old roll-ball carnival game, racing penises instead of horses. On the floor below, amidst the Linda Lovelace exhibit, McElroy’s electro band The Adversary performed in front of trippy video projections. Downstairs, in the library lounge of MoSex’s Play restaurant, a PVC-bound dominatrix flogged a man and locked him in a dog cage while heels cooled on Georgio the Human Carpet.

The party’s attendees included members of the so-called Zand Collective (which just got a shoutout as one of Paper‘s “Favorite Nightlife Movers and Shakers”) as well as other outré personalities from the Burning Man, underground trap rave, S&M, goth, drag, cabaret and club-kid scenes: Michael Musto, Muffinhead, Daughters of Devotion, , Nicky Ottav, Chris of Hur, Scarlet Envy, Ava Patron, Johanna Constantine, Wren Britton, Markus Kelly and Anna Evans. We even saw the creepy old guy who, the previous night, had been stark naked in BangOn’s haunted house.

The party continues this Saturday with a “laytexxx edition.” One caveat: Saturday’s entry was $30 in advance and $40 at the door, and the drinks weren’t cheap — so make sure your costume has some reasonably deep pockets.