In plenty of packages that need to stay good and dry -- including some types of dried food -- you'll find little packages that say "do not eat." This is why you should definitely follow that advice.
Inside those packs typically lurks silica gel, which sucks up moisture by adsorption -- where water adheres to the surface of the material. In fact, a single grain can suck up 40 per cent of its own weight in H20. And that's why you shouldn't eat it: while it won't kill you, it will suck up pretty much all of the moisture in your mouth and -- if you get that far -- throat. Which, SciShow claims, would make the Cinnamon Challenge look like a walk in the park. Gulp. [SciShow]