Compressed air tablet - is this possible?

No, it can't. Anything that would fit into a single capsule to swallow would have to be kept at extremely low temperatures. Nitrogen, for example, has a wonderful property of expansion, it's what makes engines work. Liquid nitrogen must be so cold that it kills anything living it touches on contact, but would expand greatly when heated. However, I doubt you would enjoy swallowing something in the hundreds of negatives Fahrenheit.

You can make pills filled with Baking Powder easily, and those can swell your stomach up pretty big. You can stretch a great deal, it would take a tremendous amount of pressure to burst you and you would be throwing up/burping long before then anyway.

P.S. humans don't exactly explode, in any form. if it did burst, it would rupture, and the gas would just leak out into other parts of your body. There really isn't a way to make someone fully inflate like that. They would just suffer hemorrhaging and internal bleeding, with their stomach poisoning their other organs.

I still like it as a plot device, but reality it ain't.

I saw that Bond movie too. Live and Let Die, right? Yaphet Kotto, the shark pellet, underwater final scene?

also neutron star matter is naturally that dense, it won't 'decompress' when swallowed ;)

I've thought about this a lot, and whereas an actual compressed air tablet is probably not possible, i can think of other approaches. Firstly, the element palladium can absorb 900 times its own volume of hydrogen. Therefore, if this could be released, a solid pellet of palladium or maybe some combination of substances would only need to be the size of a teaspoon to fill the stomach with hydrogen. A paste consisting of a liquid containing granules of similar such substances would release a whole load of gas.

Another possibility is the issue of clathrate compounds. These are substances whose molecules act as cages for other molecules or atoms. I can envisage hydrochloric acid acting on these, breaking them up and releasing gas.

Then there's diet coke and mentoes. The important ingredients seem to be carbon dioxide, gum arabic, aspartame and caffeine, and the combination of many sites where bubbles can form lead to the release of large quantities of gas. This strongly suggests something like a gas pellet really is possible.

Finally, a substance might be possible whose molecules could reconfigure themselves as larger ones. They could be folded up like one of those balls which can expand into spheres, for example. Proteins are usually folded, though not necessarily in this way.

Since all of this is going on in the digestive system, digestive enzymes or hydrochloric acid could trigger off some kind of reaction. However, considering this is probably going on in the stomach, the gastric acid would leak out and there's also the possibility of faecal peritonitis or gas embolism. However, there are other potential spaces in the body, and the best bet is probably between the deep and superficial fascia, where fat is normally stored. Inflation could happen here without killing the victim, i think.

Pure science fiction, most of that was completely inaccurate. Nothing we have in this current age of science can contain enough pressurized gas, and if you somehow could unleashing it would have the same effect as detonating a bomb, no inflation really. The nearest thing would be hydro-gel, which could absorb your bodies water. Granted, it might dehydrate you. Also, any real type of inflation would be potentially deadly. No real safe way to do it without injuring yourself at the least.

Well that is a very realistic (and fun) method. A lot of air escapes via your nose and mouth since you need to breathe, you also inhale a lot and exhale it. So I used to use compressors for beds and even then it was slow inflation, but you could fill up large. My lovely female friend discovered balloons in the ass is a safe and fun method, along with those pills I have said I created, I mailed her a bunch.

Then you are doing it very wrong. That much PSI is dangerous if you could direct it all inside of you, so the act of inhaling and exhaling it along with leakage out the nose is a safeguard, the rest trickles down your throat and into your belly.

You shouldn't feel pressure inside your head or chest.

Most people seem to do it the "other way", if at all, and find it difficult by mouth, but i would say the opposite is so. Concerning drinks, i would be concerned about acid-base balance and aspartame, among other things.