I guess it is rather bizarre. But most of the unusual conventions on IRC and other chat services are in order to make it more like a face to face conversation. They generally either allow you to narrate yourself from a third person perspective, or speed up common interactions that take much longer to type than they do in real life.

Although "nodnod" seems unusually nonsensical, since it takes longer to type than "yes". I cannot say I have seen that used before.