What is a weird sub you know of but most people don't? PART II

Continued from here:

https://www.reddit.com/r/AskReddit/comments/59ne9g/what_is_a_weird_sub_you_know_of_but_most_people/dgq0hd8/

(note: the top comment in this count is what brought us u/piyushsharma301)