For instance, social media personality Toni Fowler posted a photo with the lines connecting her to her partner Vince Flores and Aron Manalo, both of whom she shares a child with.

“Dalawang naanakan ako,” she wrote in the caption.

A local vet also shared a photo with several red lines among neutered cats. “Ming tama ka [na],” he joked.

What are these lines for, and where did they come from?

S Line

The trend spreading across social media comes from the dystopian K-Drama S Line. These so-called “S-Lines,” are invisible lines that tie people to their sexual partners.

In the provocative series, a girl is the only one who sees them until a pair of glasses that gives people the same power is developed. This plunges Korea into a crisis. With societal boundaries broken down, the girl, with a team of detectives, must stop the crisis and find the person behind the glasses

“The main theme that audiences should take away is how human society would collapse when the boundaries are stepped on,” director Ahn Joo Young told Deadline in an April interview.

“At its core, this is a story about people. It centers on how desires shift once someone starts seeing the S-Line,” she said in a July press conference, as per Allkpop.

S Line, based on a Webtoon by NOMABI, was first released on July 11 and has been making the rounds for its unique, unconventional theme surrounding sexual shame. The series, starring Lee Soo Hyuk, Lee Da Hee, and Arin, has also generated buzz internationally as it was selected for the Canneseries competition, where it won Best Music.

While it’s not streaming on Netflix, Disney+, or Viu, the show can be watched on the Korean platform Wavve.