The first sequel to Stallone's hit film 'Rambo: First Blood' sends Rambo on a mission to rescue American soldiers missing in action. They decided not to call the second film 'Rambo: Second Blood' in order to avoid any possibility of one of the sequels being named 'Rambo: 8th Blood' which might sound a bit silly. I doubt they would name a sequel to Se7en, 'Ei8ht', either.