Eternal September
Eternal September is a slang born from the Usenet days, when ISP started providing Internet and Usenet (usenet) access to many new users all of a sudden.
Before, joining rate was low, and new users would learn and adapt to the cultural online conventions of the experienced users.
The only exception was in September’s, when batches of new students would join Universities with Internet access, causing an imbalance in the forums with noise and lousy behaviors.
In the 80s ISP started providing much wider Internet access to new users. This caused Usenet to be flooded with new, inexperienced users every month, making it seem like it was “always September”