Batter has hit the ball to the outfield and first baseman has just caught it after it was thrown back; however, the runner has already crossed the base. Had thought at first this was a shot taken at third, but runner isn't allowed to overrun 3rd base.
Lost some quality cropping this down. Used only a 1 megapixel camera and after cropping, well, it lost some of its charm. I like the base coach's expression of urgency, though, so I've decided to make it a keeper. :)