Masturbating.

Masturbating is a practice that both men and women see as one of the most private of actions. We may understand that "everyone does it" and "it's natural," nevertheless, we treat it as though if anyone discovered that one might practice masturbation they would be labeled sexually deviant, sexually indulgent, or even as a person who can't get any from another person. Could it be possible that masturbation is an action one might make in order to make agency for themselves. No one is telling them to go and masturbate, no one (especially at our age) is directly telling them not to, for the most part. One might practice this body practice in privacy because it is their practice onto their own bodies, and they are able to give themselves pleasure.
Bringing masturbation out for anyone to see or know about would take away from the self agency of giving yourself pleasure all alone. With the practice of masturbation being entirely within the private sphere, it disallows the practice to be read as something, or turning the body practicing into an intelligible body. A body that can be read by the praxis the body takes part in.
Masturbation could be looked at and argues to be outside the limits of what a Docile body is. The body makes a choice to do something privately to give themselves pleasure. The action itself could be argued as not a docile body practice, however, it could be the docile body that makes the practice of masturbation need to be done in the private sphere.