One of my biggest pet peeves during tennis matches is the shoddy treatment some players give to the ballkids. They rudely point for towels, impatiently snap for specific balls before serves and roll their eyes if one of the boys or girls happen to stumble while retrieving a ball. There's no need to name names; if you watch the sport you know which players I'm talking about.
That's why it's so refreshing to see big-time players have some positive interactions with the young volunteers. As an example, here's Juan Martin Del Potro, the 2009 US Open champion, doing this in his fourth-round match against world No. 1 Rafael Nadal earlier this week: