The term 'shoulder' means 1: lift onto one's shoulders; 2: a cut of meat including the upper joint of the foreleg; 3: carry a burden, either real or metaphoric; 4: a narrow edge of land (usually...
it means to lower one shoulder. Usually when your driving on someone in basketball, or running the ball in football. You do it when you are charging at someone, or just towards the hoop or touchdown...