Mutual
Short for mutual masturbation: two men jerking each other off or jerking off together, hands only, usually no anal.

Mutual is short for mutual masturbation: two men jerking each other off, or jerking off together side by side. On the apps it is written just like that, "mutual" or "mutual JO," and it means hands only, no anal, often no oral either. It is the simplest kind of sex there is, and for plenty of men it is the favorite.
The word can cover a range of things. Some men mean jerking each other's cocks; some mean each stroking their own while watching the other; some mean a bit of both with porn in the background. What it does not usually mean is fucking, and anyone who writes "mutual only" is being clear about that.
Where it comes from
Mutual masturbation is a plain descriptive phrase, and the shortened form is just the app economy at work: why type four words when one will do? Gay slang has had shorthand for the same thing for decades. Bruce Rodgers' 1972 dictionary The Queens' Vernacular already used JO in describing two men masturbating each other, and the JO buddy and the circle jerk belong to the same family.
Who it is for
Mutual is a staple for side guys, men who enjoy sex with men but do not do anal. It is also the classic first step for men who are new to it or still figuring it out, from the bi-curious to the DL, because it feels like less of a leap. Couples with an open-ish arrangement sometimes allow mutual and nothing else. And many gay men who do everything else still love a lazy session of mutual with a hot guy and a good video.
The step up from mutual is often frot, where hands give way to rubbing cock against cock.
The safer-sex side
Mutual masturbation is about as low-risk as sex between men gets. During the AIDS epidemic, jack-off clubs built whole parties around it precisely because oral and anal sex were left out, and health educators used those parties to spread the safe-sex message. It is still a good option when someone wants to play but skip the risks of other kinds of sex, though skin-to-skin infections such as herpes or crabs can still be passed by touch.
Related terms
Sources 2
- Green, Jonathon. "j.o., n." Green's Dictionary of Slang, online edition. https://greensdictofslang.com/entry/5cj4wpy
- Benn, Peter. "What a Wank! The Story Behind The Melbourne Wankers Group." Star Observer, 9 October 2021. https://www.starobserver.com.au/features/community-spotlight/what-a-wank-the-story-behind-the-melbourne-wankers-group/206234