[colinwilyb]

It sounds like you're describing sites with a userbase that displays unexpected behaviors compared to expectations from visitors. A business would call this institutional knowledge and company culture. In a friends group it would be called group dynamics.

2chan, 4chan, and similar seem to be a perfect example. Users rapidly creating original content, riffing on previous posts, and introducing new content is like a factory that accidentally creates a viral meme through trial and error.

What are you trying to understand by asking this question?