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"
Hetting trolled is having some one be an ass hole over a computer screen. Trolling is amazing as it is the last bastion of free speach.
I got trolled in a chat room. Some user said I was the ugluest person that ever lived. He told me that life will be nothing but hell and i will die in some sewer after bieng forgotten by everything. Getting trolled is rough but its a form of free speach that makes me happy to live in these times.