A pet toy makes a sound when bitten or squeezed by an animal. The toy contains a resilient shell that substantially surrounds the sound-producing material. The toy also contains a core constructed of an elastic material located beneath the sound-producing material. The sound-producing material is a plastic material such as polyethylene terephthalate, which deforms when external pressure is applied to it, creating sound and vibration. In an embodiment of the invention, air permeates the sound-producing material, the core is hollow, and acoustic ports are located at each end of the toy, all to enhance its sound generating characteristics. In another embodiment, a strand is attached to or passes through the core of the pet toy. In another embodiment, an elastic outer sleeve is attached to the sound-producing material at various locations between their surfaces, to reposition the sound-producing material to its original orientation after an external pressure of force is released.