Although I'm probably getting trolled, here we go:

The first one is the Y U NO guy, the face comes from a japanese comic character (published in June 2009) and the first appearance as a template comes from a tumblr site called "LOLTumblrWallpapers", the first Text was "I TXT U - Y U NO TXT BAK?!" which also explains the stupid language used, its basically just SMS speech. It is used to express the question "Why don't you...?" where you can insert anything.

The second one is the rage guy (also known as FFFFUUUUUUUUU), it was first posted in /b/ in 2008 and is used to express pure rage, thats why its often posted with the "FFFFFUUUUUUU", which can be read as a really long and loud expression of "fuck".

The last one is the trollface, it is used to express trolling to someone or something. It is something like the sarcasm sign to point out that you are trolling so that even the dumbest person on earth understands it. It first appeared on /v/ in 2008 and is since then known as the trollface, coolface or problem? face. Usage: if you were just trolling when you asked for the meaning of those guys/faces, you would have added the Trollface to the end of your post... oh wait.