Cunnilingus and fellatio are common sexual behaviors for both same sex couples and couples of different sexes. There are various combinations of positions and techniques used in oral sex, but it is the mouth and tongue that provide the pleasure in all cases. Kissing, licking, sucking and nibbling can feel good anywhere on the genitals of both men and women. The pressure (light, firm, and in between), speed (fast, slow, or changing), and the type of motion used can be varied endlessly to produce different sensations. In both practices, the warm, moist feeling of the mouth and the tongue on the genitals can be very erotic. Some enjoy a teasing, stop-start approach, while others prefer a more steady type of stimulation. In one fellatio technique, known as the Snaky-Lick Trick, the "trick" is to tease the underside of the penis head almost imperceptibly with the very tip of the tongue, just making ever so slight tongue contact with this sensitive area in one light upward lick, and then backing off for about fifteen seconds between each lick. This trick has been said to result in a powerful ejaculation in a very short time. Other methods of fellatio include sucking the glans or shaft of the penis by engulfing it in the mouth, licking at various parts of the penis and scrotum, or nibbling anywhere along the genitals. Many men enjoy having the scrotum lightly stroked during fellatio and the area just beneath the scrotum is often quite sensitive to touch or oral massage.

Some people are uncomfortable performing fellatio because they have a sensation of gagging when they take the erect penis into their mouth. This real physiological event, known as the gag reflex, is triggered by pressure at the back of the tongue or in the throat. If a man, in his excited state, pushes his penis too far into his partner's mouth, the gag reflex may take over. One way to avoid this problem is for the person giving the oral sex to grasp the penis along the shaft to control how much of it enters the mouth. Another common objection to fellatio is having the man ejaculate in his partner's mouth. A couple can agree in advance to have the man remove his penis from his partner's mouth before ejaculation. Others don't mind. They either rinse the ejaculate from their mouth right away or they swallow it. The ejaculate, on average about 4 cc, consists of proteins and sugars and reportedly contains less than 36 calories.

Cunnilingus, like fellatio, can be performed in many ways. Women's preferences vary, but commonly enjoyed techniques include gentle tongue movements over the clitoris, more rapid, focused licking, or sucking the clitoris either gently or in a rougher fashion. Other forms that women enjoy are oral stimulation of the clitoris combined with fingering of the vagina; licking and kissing of the lips just outside the vagina; having the tongue thrust in and out of the vaginal opening; and having the clitoris stimulated by hand (her own or her partner's) while oral stimulation is directed at other parts of the genitals.

Not everyone has or enjoys oral sex. Many people who try it enjoy oral sex, but others have reservations about it. These reservations tend to fall into three arenas: first, that oral sex is unhygienic; second, that there is a taboo against it; third, that it is not a true expression of femininity or masculinity.

With regard to the matter of hygiene and oral sex, neither vaginal fluid nor semen is harmful in any way. This of course is true only in persons who are not infected with a sexually transmitted disease (STD). Everyone should be sure that they themselves and their partners are free from STDs before engaging in any sexual activity. No disease can be passed by oral sex that wouldn't be transmitted by any other kind of sex. If one partner has a STD the other is likely to catch it whatever they do together sexually. In short, oral sex between healthy people is safe and clean. Another hygiene aspect that concerns some people is genital odor. Simply washing the genitals is sufficient to prepare you for any sex, including oral sex. It is not necessary for women to douche before having oral sex, but some women choose to do so. However, douching can wash away the helpful bacteria that naturally protect the vagina. In addition to a man's natural genital odors, the genitals often take on the smells of recently eaten foods. As with women, thorough washing can reduce this odor, and besides, many people find some degree of genital odor in their partner stimulating.

The notion that oral sex is taboo discourages some people from ever trying it. Oral sex has long been frowned upon and often deemed illegal. The basis for the social disapproval and legal restrictions lies in age-old religious prohibitions, which to some are still very powerful. People who accept and practice almost any of the major Western religions can therefore feel confused and guilty about engaging in oral sex, despite their knowledge that it is a safe and appropriate form of sexual expression. In the end, each individual must decide for him or her self whether to stick to the teachings of his or her religion or to act in favor of what seems personally right for them.

For some people, the issue is not conflict with their religious beliefs as much as it is a belief that it somehow compromises their masculinity or femininity. Some people incorrectly think that cunnilingus and fellatio are homosexual acts, even if experienced by heterosexual couples. While homosexual couples do engage in oral sex, so do a majority of heterosexual couples. The activity itself is neither homosexual nor heterosexual. Apart form the misconception about oral sex and homosexuality, women sometimes feel that performing oral sex can make them feel submissive, as if they are giving a service and are thereby inferior. Men sometimes feel that performing oral sex on their partner reduces their masculinity because their penis is not involved. Couples should openly discuss these issues, and if necessary seek the help of a qualified therapist.