hands_free -> hands-free is widely used.
Hands_free what?
hands_free doesn't make any sense, does it?

It is exclusively used for male orgasms/ejaculations without stimulation of the penis and therefore usually means handsfree_ejaculation.
and that's why I'd add the following aliases:

hands_free ->
hands-free ->
handsfree ->
handsfree_orgasm ->
-> handsfree_ejaculation <-

While I agree that the tag's current use is almost exclusively for ejaculation, I think it might be a good idea to use the more general "_orgasm" to allow more feminine things like boobgasms to be included as well.