I start with a VERY full colon, obtained by a large dose of psyllium husk powder every morning. After an earlier clean-out, I will not feel anything in my rectum until day 5. I have BPH, so I do a daily prostate massage in addition to taking medication. As a massager, I use a large (65 mm dia x 180 mm long) shampoo bottle. I do this in the shower.
First I soap my arsehole, then insert two fingers, one from each hand, and stretch both outer and inner sphincters. Then, soaping the shampoo bottle, I carefully ease it in, base first, to just beyond the inner sphincter. It comes out just a little dirty underneath. At this point I adopt the knee elbow position, and take a bulb syringe with about 20 ml of water in it - the rest, air- and insert this vertically, squeezing it fully, and following with further insertions until I begin to fart uncontrollably. In this position, my descending colon is almost vertical, and the contents sag towards my rib cage.
Once more I insert my shampoo bottle massager, this time thrusting it fully home, so that only the top of its cap can be felt within my anus. The idea is to get the colon contents well away from where I'll be massaging, to keep things clean.
Now I can stand up, leaving the massager in place until after I have washed myself. Then, when all urge to bear down has dissipated, I can massage my prostate easily; and it feels great!
The displaced shit stays put. It does not immediately move down again and the shampoo bottle is hardly dirty.
I can repeat this process each night for a minimum of 9 nights, but it has gone as far as 11.
I shower at night and after it, lie flat on a towel on my back. I can feel the lower end of the turd through my abdominal wall and can push the mass quite a long way up the colon, until I feel its upper end poking my ribs. Then, finding its upper end with my other hand, I deliberately compress it as much as possible, causing it to become shorter and wider. This expands the descending colon, but doesn't bother me.
The net result is a VERY large firm turd that takes an enema to move it! After expelling that enema, I have a sloppy colon that will hold a full 8 litres of rinse water and it adds 8 Kg to my weight. Crazy? I love it.