"I read online a few weeks ago that there was a bag of snakes left on the F train," says an anonymous subway commuter from off-camera.

"Somebody left them?" says a surprised straphanger, texting while two snakes twine and curl around his neck. "Wow."

Nicole Brunelle, a finance industry recruiter, bumped into this guy last week, on a midday F train headed into Manhattan from the 7th Avenue stop in Park Slope. "I just had my first initiation into the snakes on a train phenomenon? Trend?" she told us afterwards, via e-mail. "I initially thought there was one long snake who had intertwined itself around his caretaker's neck. However, there were actually two snakes who apparently just really liked snuggling, as I should have noted from the two heads."

Maybe they're brother and sister? Nope. According to their owner, these two are actually "boyfriend and girlfriend."

Emboldened, Brunelle asked all of her burning, snake-related questions, like, "What happens when they smell perfume?" (Apparently they don't like it, and pull their heads back.)

But probably the most important subway-etiquette takeaway from all of this, is that once a free-range subway snake has twirled itself around your neck like some sort of deadly, late-summer scarf, you should definitely stop expounding about snake behavior to your fellow straphangers. "See what he's doing to my throat right now? I'm talking, and he gets nervous," says our fearless caretaker friend. "He's squeezing right now, and I have to pull him off." Why? "Because he'll choke the fight out of you."

Having survived her first snake-infested F train commute, Brunelle wondered, "What is the proper protocol for a relentless snake person the F train?" And, "Is this even legal?"

According to the MTA's rules of conduct, "No person may bring any animal on or into any conveyance or facility unless enclosed in a container and carried in a manner which would not annoy other passengers."

Last summer, when the snakes-on-a-train trend was still fresh, MTA spokesman Adam Lisberg tried to placate us. "Fortunately, this is not a regular enough issue that we need Samuel L. Jackson to record an automated announcement for subway cars about it," he said.