You might have seen plenty of updates on your timeline, people would have been updating their posts with Facebook Stickers. It's pretty cool, right? If you are confused how to do this, then it's pretty simple.
Open your Facebook mobile app, click on the status box and go to "Feeling/Activity". Now just pick the "Stickers" tab, and you'll be able to find all the Stickers you have. You can simply select the stickers you like and post it as an update. Thanks to "Trash Doves" sticker... this is getting pretty popular these days.
Update: Now you can do this on your browser itself!