Roll After Dark

Enema

Warm water into the rectum, small volume, gravity — never a shower hose.

Why people do it
A very direct kind of internal control, and a long build-up with a firm end point. For many people the appeal is the surrender involved in it rather than the sensation.
Smallest way in
A small volume of plain warm water from a purpose-made bag, and a bathroom nearby.
What to watch
Body-temperature plain water only — never soap, never a shower hose, never anything under pressure. Small volumes. Stop at cramping. Repeated use is genuinely bad for you, so keep it occasional.
In the planner
3 different things carry this tag, and switching it off removes every one of them. The mildest of them sits at hard.