There are basically two reasons to clean out before playing. First of all, a lot of guys don't like the idea of their partners or themselves coming into contact with shit. The second, is that depending on what you've been eating, it can be quite abrasive and make both the walls of the rectum and sometimes the skin of the hand sensitive. Recently, very hi-tech methods of cleaning out have been developed, including a suppository which foams, fills you with carbon-dioxide, and somehow allows you to expel more effectively than with other methods. I'm not going to describe these, as I have absolutely no personal experience of them, and what I've heard second hand, has led me to doubt their worth.

I'm going to stick to describing the good old fashioned method of douching. This involves repeatedly filling the rectum with water, and expelling it and any material in there. The simplest equipment for this is a small hand shower which has had the shower head removed, leaving the end of the hose clear. The end of the hose must be carefully smoothed, ensuring that there are no sharp edges which might damage the fragile tissues. The more advanced system, is the shower shot, which attaches to the end of a fixed shower hose. It's easily inserted and allows much more simple control of the filling up process. One drawback can be, that some bathrooms have no toilet. The result is that whatever comes out with the water, will end up in the bath, and there may be a bit of a clean-up operation needed.

An alternative, which doesn't rely on a fixed water supply, is to use a bulb douche. This consists of a large rubber or silicon bulb with a long firm tube, which can be used to squirt water into the rectum. Its advantage is that it's easily transportable, doesn't rely on compatible plumbing (this is a particular concern for international travelers) and can also be used to deeply lubricate a hole. Some guys are able to clean out simply be repeatedly filled and emptying over a short period of time. As with all things though, individuals vary. Some guys find that cleaning out thoroughly a couple of hours ahead of time, then briefly repeating the process shortly before play begins, works best for them.

Be aware of the sort of things you eat for a day or so before the action is due to take place. Many guys find that increasing their fiber intake makes the cleaning out job easier, even though there tends to be more to clean out. Some guys also prefer to fast on the day of play, on the basis that after they've cleaned out, there's less in there to make an appearance later. This has some element of truth to it, but due to the great length of the gut, in the normal course of events it's never completely empty, so the possibility of repeat cleaning being necessary is always there.

If you have difficulty getting clean enough, it's worth filling yourself partially, holding it, and lying down or even raising the hips slightly. This allows gravity to work in your favor, and moves the water more deeply into the gut. You'll find that expelling after deep filling will take longer, and water will continue to make its way down for some time, but once you're used to it, you'll learn to know when its all out. Doing this repeatedly over a period of a couple of hours, with 15-20 min breaks, will in most guys clean out deeply and effectively.

It's also worth taking a moment to think about the shape of the gut, and where it lies in the abdomen. Tracing the route upward from the anus, the rectum generally slopes toward the guy's left, kinks slightly, and moves up the left hand side of the body as the descending colon until it turns a corner more or less under the bottom of the rib cage. Lying on your left side will again help gravity to help in the cleaning process, by letting the water enter the descending colon more easily.  No matter how careful the cleaning out, nothing can guarantee cleanliness, especially with deep or heavy fisting.  No real fister will be phased by this, and will simply scoop it out and carry on. Wishing to be as clean as possible is understandable and reasonable, but fisting really isn't an activity for anyone who is paranoid about coming into contact with shit.

taken from The Art of Fisting - Jack Morin, Ph.D.