What you may actually have is just a normal disorder of ADHD. Don't worry, your not gonna grow another finger if you think about it for too long. No, the brain picks up things you hear from anything in 1 day and processes them either into a thought, a memory or a play if you will. Even if you aren't thinking about it frequently at night, the neurons in your brain become really active especially in the frontal lobe which is where the thought processing and memory is. The brain will think about events like today and create a dream that expresses the idea in your own way.
Its because dreams are caused by memories, when you go to sleep, only half of your brain does this is the part that thinks usually in imagery and logical thinking, while the other half stays awake storing your memories from that day so that they can be called upon and remembered in the order that they had happened.
The part of the brain reacts to this memory sorting negatively, trying to make sense out of it and making the illusion that is a dream, forming a situation from the memories that you had from that previous day so that it would make sense to the asleep part of the brain.
Therefore I think the reason you are having dreams of random scenarios from your conversations is because when the awake half of your brain is sorting the memory of your conversations/words of your conversations into your memory the asleep half doesn't really know what it means and therefore takes those words and forms the definition of them as an image in your dream, or your recollection of what that word would be represented by.