Self-fisting
Fisting is the process of putting a hand into a rectum or a vagina.
Whereas these openings are capable of taking an entire fist, time and lots of lube is required to stretch them out. Moving too fast can cause injury. So, the first time fisting is done, expectations should be low. You may not get full penetration in the first session. No problem, there’s always next time.
The first stage in fisting is usually just one or two fingers. Leave them there for a while, so the vagina or anus can get used to being stretched a bit, then, after a long while, add the third finger, and if all is OK, fourth, and finally the fifth finger. Both the recipient and the fister will feel the opening start to loosen, and if experienced, they will know when it is time to push on.
Vaginal fisting stops at the wrist. The vaginal cavity is only so large. One can feel the cervix with the fingertips, and potentially one could stick a finger in the os, the opening of the cervix. However, this is painful for most women.
Most anal fisting stops at the wrist. But deeper fisting is possible. Some people have been able to accept an arm all the way to the elbow. This is not easy. About 10 inches (25 cm) in, there is a restriction at the top of the rectum, where it bends and becomes the descending colon. Care must be taken to work past this restriction.
In masturbation, deep fisting is nearly impossible, but with practice, most people are capable of working a hand into their ass or vagina.
This is a dangerous activity with potential long-term consequences, so your authors recommend that you enjoy reading about it, but restrict your own activities to just a few fingers.
