#Talk to them
Talk to them
Discuss this issue with your player's, and make it clear that you expect discussion about things that are happening in the game world to use game world terms, ideas, and actions. My DM has taken this approach, and it's helped us significantly to get more into character and feel like a part of the world. Sometimes we still forget, however, and he jokingly suggests that our characters roll dice in their world, to the confusion of everyone around them. It's a simple joke, but it prods us in the right direction when we slip up.