A Rainbow Kiss is a sexual act that involves both partners simultaneously performing oral sex on each other while the person with a uterus is on their period. Once both partners have ejaculated into each others mouths, the members of the couple kiss, mixing the menstrual blood with the semen and creating what users describe as a rainbow. The term has gone viral on TikTok, with countless videos of people reacting to what it means, but the actual meaning is never shared in those videos. The trend on TikTok doesnt involve actually performing a Rainbow Kiss, but instead simply filming yourself when you google the term. It is important to note that Rainbow Kisses are not safe and can increase the risk of sexually transmitted infections.