two_handed_masturbation is undertagged, but maybe that's a good thing for now. It doesn't yet have a wiki page, and before one is written, there are some important questions about its usage that need to be clarified.
In particular, should it count if...
- one hand is occupied with genitalia and the other hand is occupied with an anus?
- one hand is occupied with genitalia and the other hand is occupied with a boob?
- one hand is on a penis and the other hand is on balls?
- each hand is occupied with different genitalia, as can be the case with multi_penis, multi_pussy or herm?
Basically, right now, the only thing that's certain is that it should be tagged when both hands are on the same penis.
Updated