While the line between fair and foul territory is pretty well marked, the distinction is not always clear to those tasked with patrolling the surrounding area.
Take the poor, innocent ball girl from Friday's contest at Fenway Park for example.
In the fourth inning of the American League affair, Kansas City Royals first baseman Eric Hosmer hit a scorcher down the left field line.
Although the ball eventually squirted into foul territory, it did so only after crossing the fair side of the first base bag.
Unfortunately, the unnamed ball girl instinctively picked up the rolling ball -- only to realize afterward that the play was still live.
While she ultimately released hold of the baseball, Hosmer was automatically awarded second, while Royals second baseman Omar Infante was granted third.
The Red Sox eventually won the game 5-4, but the incident led to a very memorable facial expression -- one steeped in horror and embarrassment.