Fellatio describes the oral stimulation of the penis. A common technique of fellatio is to take the glans of the erect penis in the mouth while rhythmically caressing the rest of the penis with the hands; the testes and the shaft of the penis can also be licked with the tongue. Suction is often used to increase the pressure and friction exerted on the penis. As the performance of fellatio progresses, the receiver may contribute pre-ejaculatory fluid to the saliva of the giver, resulting in a more lubricated penis and enhanced erotic experience. This fluid is produced by the Cowper's glands and is not semen, although it may contain traces of sperm.
Depending on the preference of the participants, this stimulation may produce an orgasm and ejaculation of semen, or may just be used as a precursor to sexual intercourse (see foreplay). If the semen is accepted into the mouth it may or may not be swallowed (hence the slang phrase, spit or swallow). Alternatively, providers of fellatio averse to receiving semen in their mouth can shift stimulation from mouth to hand once the male's orgasm is imminent. An infrequent side effect of ejaculating into the mouth is that the semen may be gagged upon.
While the use of the mouth to stimulate the penis, especially the glans, is a central feature of fellatio, often the partner simultaneously stimulates the shaft of the penis with his/her hand to provide the man with the feeling of the penis being enclosed. Some authorities (such as Franklin, The Ultimate Kiss, p. 62) recommend this as the preferred and most satisfying method of providing oral sex to a man. Another technique is to have the penis head go in and out of the mouth very quickly (without going down to the shaft). Also, some men find it another extra pleasure if the giver runs the tips of his/her fingernails on his erect shaft at the same time they are using their mouth, they say it offers a "tickling sensation."
Some males regard receiving oral sex as an ego boost, believing that such an act is a form of dominance over their sexual partner.
One form of fellatio is known as deep throating, after the 1972 pornographic film Deep Throat. This technique involves repressing the gag reflex and taking the entire erect penis in the mouth, the shaft bending slightly to allow the head of the penis to slide partially down the throat of the fellator. A deep throat session may even go 'balls-deep', a colloquial expression denoting that the provider of fellatio has fit the entire penis in their mouth, with deeper engorgement prevented only by the girth of the testicles.
The common slang term blow-job technically is a misnomer, as true "blowing"; i.e., the expelling of air through the mouth, is not used in fellatio as it would not be pleasurable . It is most commonly thought to reflect an intentional conflation of "suck" and "blow," technically antonyms but but both equally suitable as vulgar terms describing oral sexual activity. Further, the act of giving a blow-job is generally not properly defined as "sucking"; rather, the mouth is tensely moved up and down the penis's shaft, with the giver neither sucking nor blowing. At times, the giver may in fact use a sucking motion on the head of the penis, but this is generally not the sole form of fellatio. Some have postulated that the term is a corruption of "below-job", allegedly an old Victorian slang term that was commonly used to describe the act. However, there is a third school of thought that believes the word "blow" in "blow-job" indicates the climax of the penis (compare to blowing of a volcano).
