How do you talk on Grand Theft Auto

Conversations in gta IV do not work the same way as they do in GTA San Andreas. There is no way that Niko can be made to strike up a conversation with anyone. All comments made are just spontaneous. For example, if Niko bumps into someone, they will say all sorts of things, depending on the type of pedestrian. The same happens, for example, if Niko walks across the road against traffic and a car honks at him. He will say things like "Keep taking the medication!" and other witty phrases. But the fun is in wondering what Niko and the pedestrians are going to say next.