I think this is a good question. Because we've all experienced the benefits of an anus that lets nothing slip --- but at the same time, we've all had farts sneak out, and we've all had brown ass secretions (liquid dribblers that stain your underwear, even though you've wiped it clean).

I'm not sure what the answer is. I think it's 99% airtight -- i think of all the times i've had the squirts, and in spite of the fact that its pure liquid shit, my ass has been able to hold it in.

At the same time, I think of fart escapees, and the aformentioned ass secretions, and I'm not so sure. So I say 99%.

Uhm... how did the experiment go?

Well, As the old saying goes about the frog with a water-tight sphincter....

I think that it's air and waterproof to a certain extent, i mean if the pressures too strong, the levy is gonna break (unless you stick your finger in it)

The rectum actually has special nerves known as proprioceptors, that function as "strain gauges". As the, um, area becomes more and more distended the urge to dump begins. Same thing happens in your stomach, that's how you know you feel full. When the material in the rectum is solid, the smooth muscle of the lower colon is unable to compact it, so your brain gets the message to "batten the hatches". If, however, there's a pocket of gas, the muscles are able to "squeeze" it because gas is compressible. This lets your brain know that it's okay to open the gate to vent the gas. It's a really elegant system when you think about it...only one problem:

Liquid's are compressible too.

SPLAT!

I think the anus is airtight, but doesn't have a strong seal. I mean, when was the last time a breeze blew right up your ass? And at least for me, not just any fart gets out. But apply pressure, both ways, and air, liquid, or solid easily exits/enters the ass. Farts and poop usually have to be pushed. Of course this theory becomes completely null and void in the case of diarrhea. And for the record, I did have air enter my ass once. One of my coworkers shot my ass with an air hose. It was like a reverse fart.

And the experiment. I don't know If Dave's posting the official results, but I'll just say we didn't poop the same. Dave really needed a partner less regular than me for that. I'm überregular.

What about that guy, "Le Petomane?" Surely PoopReport denizens have heard of him. He was a French man in the late(?) 1800's who was quite a hit because he could control his sphincter and "suck in" great quantities of air, which he would then fart out to the entertainment of crowds. I think he could also suck up water. This is unusual, of course, and it was a voluntary thing. I think the anus is somewhat airtight, with mostly "one-way" exceptions, which break the airtightness due to (partially) voluntary muscle release.

If you're swimming, water doesn't go up your ass, and I assume water pressure is probably greater than air pressure. But of course for the anus to be airtight, it has to be airtight both ways, doesn't it? The contents of our colons are probably under greater pressure than the surrounding air, or at least I'd think so. If that's true, our muscles must be pretty strong.

Yes, the anus is airtight. I used to scuba dive, and I once was 95 feet down on a shipwreck. At that depth, the pressure is three times normal air pressure, and no water went up my butt. So, the human anus can handle at least three times normal air pressure. That says something about the amount of pressure that must be built up in your colon when you lose control of a really messy shit!

poop is verry contagest. i get constipated all the time. when youre poop is green,pink,yellow,red and brown you are in a bad mood?

youre butt is not air tight becuaus you poop monster poop monster poop monster fart fart fart kakastaine

AssBlaster2000, I'd be very interested in hearing more about your co-worker "shooting" your arse with an air-hose...

I like poop a lot and i thinkt ha there is nothingwrong with talking about poop!!!

I have hoilday poop!! my poop changes colors as the holidays change.They are also really big,and sometimes they dont go down and then i have to be=reak them up with my hands to go down!!!!

It should be airtight unless you screw through the anus all the time. Some people loosen up with age but I have never had a leaky ass.

When I was in Boy Scouts and on one of our 50 mile hikes, we ate alot of freeze dried food. I think that was the first time I experienced a "black and tan" shit.

As far as the butt seal goes, when I lived in Texas, my buddy told me that his mom said "Oh, I got water up my butt" after going down the "speed slide" at a water slide park.

Seriously people, isn't taking a dump one of the greatest things? Unless it is a skanky diarreah after eating a can of jalepeno peppers of course.

For me, the best things in life are: being wasted, taking a good dump, sex and masturbation. I haven't yet decided in what order, but a good dump is a job well done. Personally, I prefer the ones that, when I wipe and check out the paper to see if it's clean, reveal that there was nothing to wipe. (can I say all of that?)

Ah, yes. The no-wiper. I love those, too.

Forget about the no-need-to-wipe miracles. The
envelope please: There is nothing to equal the
one in a thousand dump which is so hydrodynamically exact
that is goes right through the societal anus, i.e. over the u-bend and away. Shocking you when you stand (yes, I'm a stander) & check, the bowl is empty. Zen moment!

Swish!

Your anus is only air tight when the pressure from inside is not too great. I also think age has something to do with it. I once (15 years ago) held on to a huge load for at least half an hour while walking. I remember well as it was the first day of a new job and wouldn't excuse myself from my boss during orientation.In the last two year, I have had several accidents without diarrhea. The quantity is also a factor. The bigger the load, the harder it is to hold.

I've experienced the benefits of an anus that lets nothing slip --- but at the same time, I've had farts sneak out, & brown ass secretions (liquid dribblers that stain your underwear, even though you've wiped it clean).

I think it's 90% airtight -- I think of all the times i've had the squirts, & in spite of the fact that its pure liquid shit, my ass has been able to hold it in.
So I think 90%, and I work at Oh My Ass Crapped Group, (tom@omacgroup.com) so I've run across these things.