I was playing doubles with friends. Both my partner and I were at the net and the opponents put a lob out of reach over my partner's head. He jumped to take a desperate swipe at it. Seeing that he was not going to be able to reach it I called for it and ran it down behind him. I then proceeded to hit a 'tweener shot (back to the net). I was looking to hit a short shot straight ahead just over the net because neither opponent was at that location.
I hit the shot just as I planned only to turn around and discover that I hit my partner square in the back. Even tho' I called the shot that went over his head, he did not switch sides, as expected, after his own failed attempt. When asked why he did not switch sides when I played the ball on his side, he weakly replied that I did not call "switch". I informed him that the call should not need to made -- it should be a given that he should switch sides in that situation.