say2 makes the message look like a sign, I know exactly what I scripted. I have used say2 in NPCs before. In fact, I submitted a house for CGM that used it, but I will be the only one able to see the results of it, if it is accepted. Also, say will work, you just have to separate it out, like this.
NPC Code:
say 2; //says the sign with index 2