Rainbow kiss is a slang term for a sex act that occurs when someone is menstruating. Usually, before a rainbow kiss, a person performs cunnilingus on a menstruating partner while they perform fellatio. After ejaculating into their partner’s mouth, the couple kisses to mix semen with menstrual blood. This kiss is called a rainbow kiss.
It gets its name because the semen and menstrual blood are said to create a rainbow when they mix together during the kiss. The rainbow kiss is a variation of snowballing, where one person collects their partner’s semen in their mouth after fellatio and passes it on through kissing.
The 69 position is the easiest position for the mutual oral sex that occurs before a rainbow kiss. To get into the 69 position, one person usually lies flat on their back. Their partner then straddles them, facing towards their partner’s feet, with their genitals in line with their partner’s mouth. The partner on top then leads forward to perform oral sex while their partner does the same. Another common variation sees both partners lying on their sides, with their heads positioned near their partners’ genitals for oral sex.
While heterosexual, cisgender couples typically perform the rainbow kiss, other couples can also adapt this sex act. For example, lesbian couples could perform cunnilingus on one another before having a rainbow kiss if one of them is menstruating. A menstruating transgender person could also perform a rainbow kiss with a partner who ejaculates.
An alternative meaning for the term rainbow kiss is a sex game, purported to be devised by adolescents. Participants playing the game of rainbow kiss wear lipsticks in different colors. They then take turns performing oral sex on a single person with a penis. The different colored marks their lipsticks make on the penis create the rainbow effect which gives the game its name.