The last room I jammed into On Account of the Flies made no sense. It was 1 am, I was tired, and I rolled on a table to see what was there. It was a cabinet, and it changed genders. Pretty much a stock dungeon trap, same thing (with a misty door instead of cabinet, as I recall) was in Tomb of Horrors. It didn't fit the tone of things at all, so it got excised yesterday. But, really, I never murder my darlings, I just put them into a deep well and pull them out again once they develop severe abandonment issues. So I'll plop it in the megadungeon somewhere.
This gender-changing trap is mildly different, in that attempts to "fix" the problem by going back in just make things so much worse. There's no in-game penalties here, this is just a chance to give an adventuresome player some grief, or get some cheap laughs when the players inevitably force a henchman to give the cabinet a whirl. There's a place for juvenile behavior like this at my game table. A lot of places, really, we don't have much shame.
I do have a mild suspicion that the neutering trick may be something I read somewhere and forgot. If anybody knows of some other adventure that made use of this, please let me know.
Without further ado, here's the original room 28:
The southern wall of this room has shackles hanging from chains on the wall, and a rusting iron maiden (with door open) stands next to it.
Along the northern wall is a rotted sofa, coffee table, and a large cabinet with peeling green paint. Stenciled on the doors of the cabinet are the words “Enter For New Pleasures”. The cabinet stands seven feet tall, and is big enough to hold a man. Should someone step inside and close the doors, they will find their gender switched. Stepping inside a second time to try to undo the effect will result in the subject being entirely unsexed. Subsequent visits to the cabinet by an unsexed individual will result in no change to their condition.