“Colorless green ideas sleep furiously” is a sentence composed by Noam Chomsky in 1957 as an example of a sentence whose grammar (logical form) is correct but whose semantics are nonsensical, and therefore has no meaning to understand. An example of a category mistake, it was used to show inadequacy of the then-popular probabilistic models of grammar, and the need for more structured models.

A poem and an image.

The most important thing we’ve learned,
So far as children are concerned,
Is never, NEVER, NEVER let
Them near your television set –
Or better still, just don’t install
The idiotic thing at all.

In almost every house we’ve been,
We’ve watched them gaping at the screen.
They loll and slop and lounge about,
And stare until their eyes pop out.

(Last week in someone’s place we saw
A dozen eyeballs on the floor.)
They sit and stare and stare and sit
Until they’re hypnotised by it,
Until they’re absolutely drunk
With all that shocking ghastly junk.