When one rigid object (the pusher) pushes another (the slider) across a horizontal support plane, Coulomb's law admits some surprising phenomena. First, it is possible to move the slider by moving the pusher away from the slider: pulling. Second, it is possible to obtain slip between the two objects even with an infinite coefficient of friction. Thus the common conception that infinite friction prevents slip is in error. This paper shows examples of the phenomena with both quasi-static and dynamic analysis. It also addresses implications for the concept of perfectly rough surfaces.