The Shepherd-Boy and the Wolf

A Shepherd-Boy who kept his flock a little way from a village, for some time amused himself with this sport: he would call loudly on the villagers to come to his help, crying, "Wolf! wolf! the wolves are among my lambs!" Twice, three times, the villagers were startled, and hurried out, and went back laughed at, when finally the wolves really did come. And as the wolves made way with the flock, he ran crying for help, they supposed him only at his old joke, and paid no attention. And so he lost all his flock.

It only shows that people who tell lies get this for their pains, that nobody believes them when they speak the truth.