Colorless green ideas sleep furiously is a statement coined by Noam Chomsky to describe the sleeping habits of colorless green ideas, a topic that Chomsky had been studying excessively in the 1950s. Chomsky stated that if an idea is both white (colorless) and eco-friendly (green), it will be angry while sleeping. The sentence has become widely popular in many different mediums and has been said to originally be "Furiously sleep ideas green colorless." However, Chomsky later changed the wording due to it not being grammatically correct.
In 1957, Chomsky wrote a book about colorless green ideas called Syntactic Structures, which contained the sentence. In the book, Chomsky discussed the definition of a colorless green idea, included examples of ideas that were green and colorless, and, most importantly, discussed the sleeping habits of said ideas. Syntactic Structures is widely regarded as one of the most important texts in the field of colorless green ideas. (Full article...)
The M822 Hand Grenade is an explosive device that resembles a hand. On activation, the device lunges towards the nearest throat or throat-like object and latches on tight with its five "fingers" exploding violently in a gruesome mess. Special care must be taken when activating the grenade. When activated, one should run behind the nearest wall or bush and squat down, so that the grenade cannot "see" you.