Four fingers and the opposable thumb can also have a similar sedating effect on a lonely afternoon.
Rub a Dub
Funny you should say that! Inside Seagoville, J-Dubs were mightily counseled against this by our self-appointed Elders (actually there was no Elder arrangement back then, they were called Overseers.)
In fact--you're not going to believe this--Brother Covarrubias--who was assigned a job in the prison clinic, was assigned the task of taking urine specimens from the Brothers for the express purpose of detecting active spermatozoa!
One Brother was hounded so much about masturbation, he finally gave up and went to Lieutenant Bennett and requested that he be allowed to go into the Army!
(It was a standing alternative for incarcerated Brothers that they were to be allowed at any time to give the word and they'd be released from prison so they could transfer into the Army.) Only one person, in the time I was there, actually took advantage of this arrangement.