Swinging

Swinging is a non-monogamous behavior in which people, single or partnered, engage in sexual activities with others as a recreational or social activity. It is similar to open relationships, but commonly conducted as an organized social activity. An example would include one who has sexual relations with other people, due to their partner being infertile and unable to reproduce.

History
The phenomenon of swinging, or at least its wider discussion and practice, is regarded by some as arising from the freer attitudes to sexual activity after the sexual revolution of the 1960s, the invention and availability of the contraceptive pill, and the emergence of treatments for many of the sexually transmitted diseases that were known at that time.

Flag
The flag was coined by DeviantArt user NonMonoPrideFlags on November 28th, 2015. It has no confirmed meaning.

Resources
https://en.wikipedia.org/wiki/Swinging_(sexual_practice)