What is what's a rainbow kiss?

A "rainbow kiss" is a purported sex act that involves one partner performing oral sex on another and then, after the oral sex, both partners exchange blood from their mouths through kissing. The act's alleged result is a mixing of blood, creating a colorful effect, hence the name.

It is widely considered to be an urban legend or a sexual myth. There is no evidence that it is a real or common practice. It's mainly spread through online forums and discussions.

The alleged practice carries significant health risks. The exchange of blood can transmit various bloodborne diseases, including HIV, hepatitis, and other infections.