Bully Sticks, generally referred to as "pizzle sticks", seem to be gaining in popularity just based on how many stores are now selling them.

These dog treats are made from 100% bull penises, and are often compared to rawhide and pig ears, offering hours of chew time and delicious flavor.

A company called, Bullysticks.com, a subsidiary of Knine Kountry Distributing, recently moved into a new 10,000 square foot facility accommodate growth.

The company, which measures its productivity in inches, claims to have sold 5 million inches to date.

Bully Sticks, which are easily digestible and low in fat, is also high source of taurine, an amino acid used in energy drinks such as Red Bull. In fact, taurine was first discovered in bulls.

Bullysticks.com says their raw materials come from South America, and go through a fairly simplified manufacturing process. They're sterilized, dried and then smoked for flavor. The company offers the product in various shapes and sizes, one of which includes the "Jumbo Bully Stick".

Bully Sticks are sold in most pet supply stores, and can be purchased directly from Bullysticks.com.