If someone constantly talks about things for no real reason, I like to talk about things that make them uncomfortable. It's one thing to speak about relationships when there is big news, but nobody wants to hear every little detail. If you start talking about how your food took too long when you and your girlfriend were out at dinner last night, and she was upset all evening, then I'm going to start talking about my penis, the joys of knitting, or my plan on how I would murder them and dispose of the body if the need arose.