As was rumoured earlier this month, Facebook has gone ahead and launched a standalone app which allows for anonymous posting.
Facebook Rooms is an iOS app (there's an Android version coming later) which allows a user to choose a completely anonymous user name (you don't have to give the app your real name at all), and start up a group chat room to discuss any topic they like (and of course, being anonymous it could be any topic under the sun including potentially embarrassing things like, for example, your sex life).
So yes, essentially it's an old-style web chat room on your new-style smartphone, with the "room" being a feed of not just text but photos and videos. The topic of a room is set by the creator, and anyone will be able to join these group chats, not just your circle of friends on Facebook, though you can set limits on who joins if you wish and customise member permissions.
You can customise quite a lot, in fact, fiddling with the text and emoji on your Like button for example, or you can switch the colour scheme, add a cover photo and so forth.
Also, you can use a different name for each room you join, so you don't even have to keep the same user name across the Rooms app, you can have multiple identitities.
The app comes from the minds of Facebook Creative Labs, and apparently early users have created rooms for beat boxing videos, parkour (otherwise known as leaping around shopping centres like an idiot), and "Kicks From Above", a room dedicated to photos of cool shoes in cool places (lots of Arctic snow boots then, presumably).
Facebook product manager Josh Miller, who headed up the app, said in a blog post: "One of the things our team loves most about the internet is its potential to let us be whoever we want to be. It doesn't matter where you live, what you look like or how old you are – all of us are the same size and shape online."
"This can be liberating, but only if we have places that let us break away from the constraints of our everyday selves. We want the rooms you create to be freeing in this way. From unique obsessions and unconventional hobbies, to personal finance and health-related issues – you can celebrate the sides of yourself that you don't always show to your friends."