So, I know the subject has come up time and time again about wam substances getting up the vagina, and it seems like the general consensus from those who are well acustomed is that there's nothing inherently dangerous about getting mud and chocolate up one's pussy. (just make sure to figure out your own sensitivities first, and whatever you do, do not douche!)
However, I do not recall seeing a similar thread about getting wam substances up your asshole. And since this question is far more relevant to me, I figured I might as well ask. My assumption is that there likewise is nothing inherently dangerous about getting stuff up there, and that once again, it'll come down to personal sensitivies and some other caveats I should know about beforehand.
However, i am not one to trust my own judgement, especially if I am not at all informed. So I leave it to you, UMD, to hopefully answer my question.
The rectum and colon have a direct connection to the bloodstream. If you wouldn't eat it, don't put it in your butt.
There are some things you should never put in your ass. Glue slime with borax is poisonous, a huge no no. I find that shaving cream or soap burn and are not internally safe. Any toxic ingredients should never go there. Avoid anything with bacteria such as eggs or natural mud, as these can distrupt the healthy gut bacteria and possibly cause infection.
However, most wam substances are completely fine. Any cellulose gunge, cake batter, syrups, or other foods are ok. Mud from pottery clay causes myself some discomfort, but everyone is different and has different sensitivities. If you're not sure of a certain substance, research the ingredients and if any of them are toxic.
I've gotten quarry mud (clay) up my ass quite a few times, with no issues (and it feels good too), but agree that more natural mud, like around a swamp or pond, isn't the best idea. Still, I've done that a couple times with no issue. The comment that if you wouldn't eat it, don't put it up there, is a good one...since you'll absorb it! Also agree that shaving cream will not feel good.
I have done many messy wedgies using cool whip , frosting, icecream, chocolate syrup, oatmeal, shaving foam and pudding I have had no issues with mess getting in my ass. Unless your allergic to a substance I don't see you having any problems. I have also used toys that have mess on them. As long as you wash your ass (like you should be doing anyway) you should be fine.
Plain yogurt tends to be one of the safer things (and good for you), but it's just okay as an anal lube, but fun if you like a bit of friction.
I've used lots of food as lube, sometimes they work too well and things go in too quickly. Custards, ice creams, mayo, other condiments, and whatever else got mixed up there. The polymers are almost all okay too. J-lube, methylcellulose, most things from messy supplies, etc...
Mud was really grainy despite how it felt in my hands, and I knew the risks before I did it. I will neither condone nor condemn it. My asshole came out fine, but can't speak for everyone. Also, bring your own potable water to wash any toys with if you go somewhere natural. If it smells funky or it's an area where dangerous bacteria or amoeba are known to be, I wouldn't risk it. I don't really do advanced play, so it didn't go in very deep and I cleaned out shortly after. I'd imagine that even if you used powdered clay, it could cause some microtears which could increase some risks for partnered play.
Don't use alcohol. Agree that soap-based lube sounds like a bad time in so many ways.
Guess the only other thing will be knowing yourself and any sensitivities that could give you a bad time.