The handkerchief code in 'American Horror Story: NYC' explained

• "American Horror Story: NYC" sees a killer hunt the LGBTQ+ community.
• Dubbed "Big Daddy," the killer uses the handkerchief code as part of his reign of terror.

Ryan Murphy is back for more terrifying delights with "American Horror Story: NYC," which sees a leather-clad serial killer called "Big Daddy" target the LGBTQ+ community.

This occurs against the backdrop of a mysterious virus ravaging Fire Island, as many men report symptoms of a rash that won't go away. After the first two episodes, it's clear this is all mirroring the HIV/AIDS crisis — and the LGBTQ+ community is at an extremely vulnerable time in New York.

The first two episodes have been a much less gory affair than previous seasons, but it's no less creepy thanks to Big Daddy, who stalks men in dark parks as well as dimly lit bars.

Part of his bizarre modus operandi involves leaving handkerchiefs in the bodies of his victims — even stuffing one into Captain Ross' (Lee Aaron Rosen) severed head.

Murphy touches on the handkerchief code when the medical examiner removes the bandana from the pilot's mouth/throat, as she briefly explains it's a way of signaling sexual preference. Gino Barelli (Joe Mantello) also tells his boyfriend, Patrick Read (Russell Tovey), about it later on in the episode.

What is the handkerchief code?

The code is more commonly referred to as the hanky code or bandana code, but the show is right: it started in the 1970s as a way for gay and bisexual men to communicate what they're seeking, their interests, and fetishes.

As per the Saint Foundation, it supposedly started in San Francisco shortly after the gold rush.

Because there weren't as many women around, men used blue bandanas when line-dancing to signify who was dancing the man's part and red for who was dancing the woman's part.

This idea would later be adopted by Alan Selby, who claimed he started the handkerchief code when his business, Leather 'n' Things, accidentally received a bulk order of bandanas, and they created the code to get rid of the excess stock.

For the moment, it's not clear why the killer has adopted the handkerchief code as part of his hunt, though it'll probably be explained later down the line once the show reveals more clues about Big Daddy's identity.

In "NYC" episode two, "Thank You For Your Service," the hulking figure is also seen outside of Sam's (Zachary Quinto) apartment, though Sam doesn't even acknowledge him.

Whether this is a hint that Sam is secretly the killer remains to be seen, though that would be predictable since Quinto previously played the serial killer Bloody Face in "American Horror Story: Asylum."

But Barbara Read gives her soon-to-be ex-husband, Patrick, a box of his belongings in episode two, which includes a number of colored bandanas, even though he previously asked Gino about their significance in episode one, "Something is Coming."

It's possible the detective was just naive and owned different bandanas, but it's definitely suspicious. However, Patrick isn't as tall and stocky as Big Daddy, so that probably rules him out of being the killer.

New episodes of "American Horror Story: NYC" air Wednesdays on FX and the next day on Hulu.