I will answer your question with a series of questions: Is the game being played in a dome? Are there fewer than two outs? Does the manager like to hit and run? How flexible is the baserunner in his midriff area? Is the baserunner's uniform made of a synthetic polymer? Additionally, this question presupposes that the baserunner does not bruise easily.
Here is how I envision the scenario: It is a night game, the ballpark lights use halo-reducing technology, the always-solid Jerry Layne is the third base umpire, Jose Reyes is dancing off third, and a barely-healthy Cole Hamels is pitching and has an Effective Pitch Count (EFE) of 27. Obviously, it is the third inning (EFE = inning * 9).
Reyes is taking a 90% lead, meaning if the pitcher threw over, he'd only be able to get back to third 9 out of 10 times. The hit and run is on, but David Wright misses the sign. The ball is hit right at Reyes with 80e velocity (where e = .001 seconds) down the third base line. Umpire Layne is watching (professional that he is) but 73% of his thoughts are dedicated to a former girlfriend of his that he'd seen on the subway while commuting to the game.
What should the Reyes do? Try to get out of the way but get hit anyway. There is no way for a human, even a Reyes human, to get out of the way of an 80e line drive if it is hit directly at Center Of Gravity (COG). Still, because Reyes is so fast, the ball merely glances off his thigh.
Under normal circumstances, a batted ball that hits a baserunner relegates the baserunner to the bench in the form of an out. But Reyes, being a smart ballplayer with a Measurable Baseball IQ (MBIQ) of over 203, has taken his lead in foul territory. Upon the batted ball's contact of Reyes' muscular thigh, Umpire Layne correctly signals a foul ball. When play is resumed, Umpire Layne resumes thinking about the auburn hair his ex was sporting. It flowed like vino la naranja.