'A "Rainbow Kiss's'" topic is one that isn't widely discussed because of how intimate it is.'To put it simply, it's a kiss shared between two people after one gives the other oral sex and one returns the favor with the other's genitals in the same way.'The term "Rainbow" comes from the combination of fluids involved.Though it may not be for everyone, it is important to remember that any act between consenting adults is perfectly legitimate, as long as safe, respectful, and pleasant for both parties concerned.