Where is the dislike button?

Facebook has been using its like button since april of 2010, first on status updates and expanded to photos, comments and shared links. Though there are a lot to like in this world, there are times when people don't agree or 'dislike's' someone else's posts or comments making users wonder, where is the dislike button?
 

So to answer that question, here's my take on part of the reason. Take YouTube for example, first off it's pretty evident that there is a dislike button, there's even a bar showing the amount of likes and dislikes. Secondly, YouTube because of the anonymity of users without videos of themselves, can post a lot of negative or hateful comments without repercussions. On top of that, having a dislike button adds fuel to fire, it insinuates people to harbour negative feelings stronger than a mere dislike. Although people are still able to post negative comments in Facebook, they are identified with a full personal profile making them perhaps more reluctant to do so and without a dislike button, they can perhaps look at things in a more positive manner.