In both the US youth lacrosse and NCAA men's lacrosse, the signal when a player commits a penalty is the same. The referee will stand with his knees slightly bent forward, in the half-crouching position. Then, the lacrosse official will lower his right hand to his side and place the fingers behind his right knee. Next, he will make a swinging motion back and forth and strike the inside of the knees, imitating a player being struck in the legs.