It is said/used after successfully tricking another person. Sometimes used to tell someone you were being sarcastic about the matter.

If used correctly, the other person should say "arms" or feel the emotion behind "arms".
James:" Hey, do you think I'm so pro in LoL?"
Jesse: "Of course, who's better then you? :3"
James: "I kno right?
Jesse: "Trollie face"
James: "ARMSSSS"
by Trollie Face March 22, 2013
Get the Trollie Face mug.