for sometime now on the Facebook Messenger
app within Messages only will be used in
comments, user can get the sticker on Facebook's
sticker store where they are grouped in packs, ranging
from Sport teams, popular games, Movies etc.

Facebook engineer 'Bob Baldwin' wrote in a post
on his timeline " "I think stickers will allow
people to reply to a variety of posts in a more
fun way than words alone,You can now easily show
your excitement for a post with good news, cheer
up a friend who's feeling down, and express a
variety of more nuanced reactions."

see full article and pictures below

http://www.naijapeepz.com/2014/10/facebook-stickers-now-available-in.html