A mass of world dominating self-reproducing nanobots
. Grey goo common end-of-the-world scenario, where malfunctioning nanobots reproduce without inhibition, consuming any available raw materials.
Grey goo can also be used to describe any number of warm breakfast cereals, such as oatmeal
, cream of wheat
, or grits
Man, when national labs release grey goo, I'm heading off to the mountains in Alaska before I get consumed alive.