I'm not certain that this was meant as humor or not, but dihydrogen monoxide is also known as water. I've never had an enema without that ingredient.
In a sense. Calling water “dihydrogen monoxide” and talking about its “dangers” is a play to point out the phenomenon of chemophobia, or a fear of unknown chemicals and strange sounding scientific names, and to show how silly it is at the end of the day. We all know water to be quite safe and incredibly mundane, but when given a “chemical” sounding name and referencing other dangerous things it can be in without the context of it being “just water”, it's suddenly scary. It's to point out that we can have a strong bias towards “chemicals”, when in reality, by definition most things are chemical, including water! And to be fearful of “chemicals” just on the basis that they're in other scary things or have other purposes is inherently absurd.
If I were to say that I would be taking an enema with a non-insignificant amount of dimethylaminopropylamine, I'm sure it'd be concerning to some. But in reality, it's an ingredient common in soaps, including those seen as free of “chemicals” or otherwise safe like castile soaps, and it comes purely from the soap-making process (and people who have ever taken a soapy enema have almost certainly had said chemical in their body already). The same is true of a lot of ingredients, including the likes the “napalm ingredient” lauric acid (which is simply a component of the fats found in things like breast milk).
This is all to say that Dove soap is absurdly far from comparable to things like engine coolant and napalm, and that people shouldn't be so scared of even attempting to use such solutions in enemas. I say all of this because, at the end of the day, I just want to spice up what's in my bag in a relatively safe manner and share that enjoyment around, and to discourage alarmist rhetoric when there's other real safety concerns to talk about.
On a happier note, I did find that Dove soap is quite decent at giving enema equipment a quick scrub over to clean, and for casual cleaning, swishing the bar in the bag and letting the “solution” run through the tubing and nozzle is a convenient way to keep equipment clean and ready. This isn't a replacement for deep sterilizing cleanings of equipment that may use bleach or the like, but it is mighty handy in a pinch and for frequent use.