That's what Toxic Megacolon means in medicine, but I believe that it could really, really shine in film; specifically in the Horror Genre.
I'll admit that it has already been done with worms in both Tremors and Dune, but Toxic Megacolon can add an Alien spin on things too. Some over-zealous scientist introduces a new 'miracle' drug that actual makes human colons become self aware and carnivorous. They erupt from people's stomachs, devour their hosts and then become hungry for more. And they are colons, so they are always hungry. They grow to enormous proportions and become capable of flight (insatiable, carnivorous, mutant, flying Toxic Megacolons). The army comes in to 'nuke the crap out of them' (pun intended), but in the explosion they morph into one giant megacolon (that looks a lot like the one on the asteroid in Star Wars). The megacolon hits an urban area (mass destruction). Finally, some scientist, who knew all along, will come in with an awesome solution (I don't know what it is yet, but it will probably be pretty predictable).
The best part: Little kids could dress up as scary Toxic Megacolons for Halloween.
