On the"Eder Dam" map, select support (recommended) and go to the base on the right side of the bridge (when looking at it from the two story house). Once there, go to the motorcycle on the left side of the base and enter it, but don't turn the handlebars at all. Simply hold B until you are all the way backed up. Exit and you will be under the hill. Stay on the grass and do not go too far back or forward or you will fall off. You can lay down and are able to shoot through the hill.