When a dog bites a male human on the penis. Sometimes, even ripping it off with it's teeth. It does not necessarily need to be a Chinese dog. It is called a Chinese Dog Bite, because several Kung Fu movies from the 1970's had these kinds of scenes. Some folks of S&M fantasize about being tortured like this. Primarily because even though the dog is biting your penis off, they are excited about the fact that something is coming in contact with it. It is considered to be stimulating.
The other day, I was thinking about getting a Chinese Dog Bite, and I quickly got a hard on.