For 30 years I've enjoyed enemas--a lot of enemas, many of them the extreme sort: high volume enemas; ultra-fast-injection-rate enemas using 1" plastic hose and 1" inside-diameter nozzles; long retention times of weird solutions; hot enemas; cold enemas. You name it, and I've probably done it when it comes to enemas, (except for those little bulb things.)
Over the last couple of years I've been doing a record number of enemas while sticking a lot of new things up my ass. I've gotten into using long colon tubes, (actually up to as long as my whole colon). I also started using a squishy soft 3" wide retention plug that fills every corner of my rectum to make high volume enemas easy, probably way too easy. I have two new extreme retention-type enema nozzles I use a lot. Both insert 11" to penetrate and seal my inner sphincter, and fill the first few inches of my sigmoid colon. My first was an 11", double-ball retention nozzle. My second is the infamous SNCMAX3, the ultimate retention nozzle. It's 11" long, 3" wide in the rectum, 2.5" wide in the lower sigmoid colon, and designed to perfectly seal both the anus and inner sphincter for effortless, no-hands retention of anything you can inject into yourself until you say uncle.
With an upcoming colonoscopy, I've been a little concerned lately about possible damage I might have done to myself with all this colon abuse. I've been imagining the worst outcomes, like the colonoscopy doctor would find that I have a heavily scared, totally inflamed, and grotesquely enlarged colon filled with infections, ulcers, fissures, multiple polyps, and maybe even cancer. I've been expecting a WTF-have-you-been-doing-to-yourself lecture from the doc after I wake up from his colonoscopy.
Well, the colonoscopy results are back. I'm fine. I just had one polyp, (not unusual for me.) It was actually an improvement from my colonoscopy five years ago in which I had internal and external hemorrhoids, and three polyps, one of which was a pre-cancer. So with great relief, I can now say that my colon is a lot more normal than I am.