The simplest answer is that the cultural information on blogs, social networks, reddit, and others tends to replicate — like a virus.

The complicated answer:

William S Burroughs formulated the idea that language is a virus and presented it in the novel The Ticket That Exploded. He expounded upon the concept in Electronic Revolution.

Burroughs thought of language as an infectious agent that by its existence exerted control over the mind. He felt the that ability for people (or even animals and machines) to think, create, and communicate is limited by the conventions of language and it’s use. Words and phrases in our native tongues are indelibly linked to the concept or thing the word or phrase ideates. What comes to mind when I say “black cat”. Most likely the first thing that comes to mind is a small black feline. It could however refer to a white horse, a dark-colored boat, a nightclub, a dominatrix’s whip, or an African-American jazz musician. Burroughs felt that ultimately, such hard associations would eventually lead to complete thought control, due to limits placed on the mind’s ability to free associate ideas, thoughts and words. He though that all possibilities would be accounted for by existing words in expected patterns.

Meanwhile on the internet, memes spread like wildfire.