A community of mothers on Tumblr. They think they are better than everyone else because they post pictures of their children on the internet. In a way, it makes up for their shitty parenting due to blogging all day. They are horrible people with (most of the time) horrible grammar. They have absolutely no logic. They prey on new mothers and like to point out flaws when they have so many themselves.
Charlie: "Do you know any Mumblrs?"
Stephanie: "Hell no, those bitches are stupid."