Milking Problem

I haven't sold one tractor all month," a tractor salesman tells his friend."That's nothing compared to my problem," his buddy replies. "I was milking my cow when its tail whips around and hits me in the forehead, so I grabbed some string and tied its tail up to the rafters. Then I go back to milk it and it kicks me in the head with its right hind leg, so I grab some rope and tie its one leg up to the rafters. I go back to try and milk it again when it kicks me in the head with its left hind leg, so I tie its other leg up to the rafters. Then my wife comes walking in and I'll tell ya, if you can convince her that I was trying to milk that cow, I'll buy a tractor off ya."