That's what I call "normal conversaion", actually... H and I, and my closest friends and I, always discuss word definitions. It always weirds me out when people don't do that! T and I spend a lot of time making sure that our words mean the same thing, and we have definitely talked about what "okay" means. I think it's a sign of respect for the other person in the conversation, that you don't waste each other's time talking about stuff that might mean different things. I don't see it as a therapeutic technique, but it's definitely a way to make a conversation more interesting and meaningful.