Neuticles are prosthetic dog nuts. No joke.
Officially - Patented Neuticles are testicular implants for pets. Neuticles are available for canines, felines, equine, bulls or any pet which is neutered. Neuticles should be implanted when the pet is neutered but can be implanted years afterwards in most cases.
Neuticles were invented by Gregg A. Miller back in the early 1990's for his dog Buck.
"Buck was seven months old and as ornery as they came. Well the day came when I had to consider neutering and was really surprised when it was discovered the testicles are permanently removed when the pet is neutered. Buck would no longer be Buck!" - Gregg Miller
Interesting Side Note: They have Neuticle key chains and necklaces if you need like a stress squeezey or something.