One of the things that my toddler daughter doesn't do yet is play ball (as in rolling it back and forth) because, well, until a couple days ago, we'd never tried. I started out rolling a ball back and forth in front of me. She got interested and came over to see what I was doing. I rolled the ball to her. She rolled it about ninety degrees from my general direction. I reached over and caught the ball and rolled it back to her. This continued for a few minutes and then somehow it became apparent that she was much more interested in chasing the ball than in a nice controlled game of roll the ball back and forth. So after a few minutes the game looked like this: mama rolling the ball across the room, little girl toddling after it, picking up the ball and carrying it back to mama. Repeat.
I had a nearly overwhelming urge to say "Go fetch!" after I rolled that ball.