Irrumatio, also called irrumation, is a type of sexual intercourse performed by actively thrusting one's penis into a partner's mouth and throat. It may also be the thrusting of the penis between the legs, feet, upper thighs (also known as interfemoral sex), or between the abdomens of two partners.

"Latin erotic terminology actually distinguishes two acts ... First, fellation, in which the man’s penis is ... orally excited by ... the ... fellatrix ..., [and] Second, irrumation ... in which the man (the irrumator) ... engages in ... motions by moving his hips and body in a rhythm of his own choice."

The English noun irrumatio or irrumation and verb irrumate come from the Latin irrumare, to force one to perform fellatio. Also note that J. L. Butrica, in his review of R. W. Hooper's edition of The Priapus Poems,a co rpus of poems known as Priapeia in Latin, states that "some Roman sexual practices, like irrumatio, lack simple English equivalents."

As the quotation from Butrica suggests, and an article by W. A. Krenkel shows, irrumatio was a widespread sexual practice in the Roman Empire. J. N. Adams states that "it was a standard joke to speak of irrumatio as a means of silencing someone".

Oral sex of any kind was considered to be an act of defilement: the mouth had a particularly defined role as the organ of oratory, as in Greece, to participate in the central public sphere, where discursive powers were of great importance. Thus, to penetrate the mouth could be taken to be a sign of massive power differential within a relationship.

Remaining frescos from the Roman city of Pompeii demonstrate that irrumatio was one of the specific Roman sexual acts, the others being fututio, fellatio, pedicatio and cunnilingus. This was probably because the extant frescos appear to be in bathhouses and brothels: oral sex was something usually practiced with prostitutes because of their lowly status.

Pedicatio and Irrumatio are referenced in Catullus 16. Still, C. A. Williams argues that it was accepted as a degrading act, even more so than anal sex. S. Tarkovsky states that despite being popular, it was thought to be a hostile act, "taken directly from the Greek, whereby the Greek men would have to force the fellatio by violence".

Furthermore as A. Richlin has shown in an article in the Journal of the History of Sexuality it was also accepted as "oral rape", a punitive act against homosexuality. Roman historian Suetonius has a passage in his De Vita Caesarum which inconclusively states that Roman emperor Tiberius took great pleasure from forcing women, even those of rank, to perform fellatio.

Mutual masturbation is a sexual act where two or more people stimulate themselves or one another sexually, usually with the hands. This may be done in situations where the participants do not feel ready, physically able, it is socially appropriate, or simply do not wish to have full sexual intercourse, but still wish to have a mutual sexual act.

It is also done as part of the full repertoire of sexual intercourse, where it may be used as an interlude, a form of foreplay or simply as an alternative activity to penetration.

For some, it is the primary sexual activity of choice above all others because it enables the individuals to see face to face and leaves the hands free to caress.

Mutual masturbation can be practiced by those of all sexual orientations. If used as an alternative to penile-vaginal penetration, the aim may be to preserve virginity or to prevent pregnancy. Some may choose it because it achieves sexual satisfaction without actual sex, possibly seeing it as an alternative to casual sex.

The techniques of mutual masturbation resemble those of simple masturbation, with the exception that other persons are involved. The range of participation can be as simple as two participants masturbating in the same room at the same time without any physical contact to a group of people all stimulating one another.

In the case of two participants, one partner may stimulate the other, each partner may stimulate the other, or one may stimulate both themselves and their partner. Mutual masturbation might result in one or more of the partners achieving orgasm.

If no bodily fluids are exchanged (as is common), mutual masturbation is a form of safer sex, and greatly reduces the risk of transmission of sexual diseases. As such it was encouraged among gay men by some safer sex organizations in the wake of the AIDS outbreak of the 1980s, as an alternative to anal or oral sex.

The terms "mutual masturbation" and "circle jerk" are sometimes also used as vulgar
metaphors. They can refer to a situation, often in the workplace, politics or academia, where people are stroking each other's ego without producing anything of value.

Partnered manual genital stroking to reach orgasm and expanded orgasm are practices done with a partner. Both people focus on creating and experiencing an orgasm in one person. Typically in this safe sex partnered masturbation practice, one person lies down, pantless, while his or her partner sits alongside.

The one partner sitting using their hands and fingers (typically with a lubricant) to slowly stroke the clitoris or penis and genitals of the partner. Expanded orgasm as a mutual masturbation technique is said to create orgasm experiences more intense and extensive than what can be described as, or included in the definition of, a regular orgasm.

It includes a range of sensations that include orgasms that are full-bodied, and orgasms that last from a few minutes to many hours.The term was coined in 1995 by Dr. Patricia Taylor.