Mutual masturbation is a sexual act where two or more people stimulate themselves or one another sexually. Just like solitary masturbation, this act depends largely upon the preferences or social constraints dominating the lives of people. Some choose to incorporate mutual masturbation into the foreplay, making it a game in which the two or more lovers can give pleasure to each other while still remaining face to face.

Others use mutual masturbation instead of intercourse, mainly as a healthy variation dictated by a diverse sex life, or in order to satisfy a fantasy. However, some people may engage in mutual masturbation because it's the best choice they have (mostly when the preservation of virginity is desired). Mutual masturbation may be carried out with or without removing one's clothes.

Fully clothed people rubbing their bodies together are said to be engaged in frottage, which is also known as "dry humping" (mainly when the partners are trying to simulate intercourse). A light form of rubbing is widely used in the modern dancing styles developed in the Caribbean cultures. The purpose of the dance is simply to be erotic and intimate and not to lead to a proper orgasm.

A group of men masturbating together is called a circle jerk. The men forming this group may or may not masturbate each other, depending upon whether the men feel like it or not. Circle jerk may also lead to various games among men, such as competitions to see who ejaculates first or, on the contrary, who can hold back the longest.

Men may also compete to see who can ejaculate farthest, who can ejaculate the most semen or simply who has the largest penis of the group. Another form of mutual masturbation is called "dog pile". A dog pile is group sex without the intercourse.

The people of both sexes who form the pile simply masturbate each other to orgasm. The modern age has also managed to add another technique to the mutual masturbation list. Despite some debate, it is generally acknowledged that two people watching each other masturbate via webcam can be said to engage in mutual masturbation.