To break guy:
If you were intently watching a movie, I wouldn't interrupt and start a conversation.
If you were intrigued by the latest episode of Bones, I'd wait until the show was over before initiating a discussion.
If you were playing a video game, I'd come back after you were done.
If I'm reading, STOP FUCKING INTERRUPTING ME. Reading is something I enjoy. Reading is something I must do. Leave me alone!