The wrenching existence of a circus sideshow attraction.
"Dog Boy has a phantom tail. When excited he can feel the invisible tail wagging; his whole rump moves with it. When he’s afraid, he tucks it between his legs. But there is something frustrating about it, like eating imaginary food. Sometimes his frustration builds until he feels the intense and sudden urge to chase this invisible tail; he spins around and around in a tight circle until he exhausts himself."