French Kiss

A French kiss, tongue kiss, pash, snog or deep kiss is a passionate romantic or sexual kiss in which one participant's tongue touches the other's tongue (or lips) and usually enters his/her mouth.
Although family members may sometimes kiss on the lips, a kiss using the tongue almost always indicates a romantic relationship. French kissing stimulates the lips, tongue and mouth, which are all areas very sensitive to touch. It is considered by many to be both very pleasurable and highly intimate. Unlike other forms of "casual" kissing (such as brief kisses of greeting or friendship), episodes of French kissing will often be prolonged, intense, and passionate. Studying animal behavior, Thierry Lodé, a evolutionary biologist, argues that the French kiss has a real function: to explore the sexual partner's immune system via the saliva. Initiating the sexual desire, the French kiss allows the partners to avoid inbreeding (see also sexual conflict).
Because of the intimacy associated with it, in many regions of the world tongue kissing in public is not acceptable to most, particularly for an extended time. For example, in Israel, legal precedent has been set for considering a French kiss without consent, as opposed to a kiss without involvement of the tongue, indecent behavior.[citation needed]
In a tongue kiss participants exchange saliva, something which would be considered disgusting in other contexts. Although most sexually transmitted diseases are not transmitted by kissing, the exchange of saliva in a French kiss may increase the chances of catching an orally transmitted disease. Infectious mononucleosis (American: Mononucleosis or, colloquially, "mono"; European: glandular fever), a disease spread through saliva, is colloquially referred to as "the kissing disease".
A French kiss is often used by lovers to express their intimate feelings toward each other, whether in passing or as a prelude to sexual intercourse (as a part of foreplay). French kissing also occurs frequently throughout actual intercourse. A French kiss is thus a highly intimate affair, and in a manner of speaking symbolizes a side of the physical love one has for the other. In essence it can also be called a passionate or loving kiss.