Shoulder swapping aim is a concept found in some third-person shooters that gives the player the option to change which shoulder they are looking over when aiming down the sights of a gun. Aiming down the sights will typically make the camera zoom in closer to the character, which can sometimes block the view of the player. Swapping shoulders can give the player an advantage when fighting enemies around walls and corners, giving the player the best view.
Certain developers tend to incorporate this concept in their games frequently. Rockstar, Naughty Dog, and IO Interactive have all used this concept numerous times.