Laughing Dog (also known as The Duck Hunt Dog and That %$!#@& Dog) is a character in the video shame known as Duck Hunt. Though he is not immortal, he has proved immune to the common rifle, a fact that is highly frustrating to both Master Chief and Player 1.
Laughing Dog was once just a stupid puppy. But then he grew up, so now he is a stupid dog. When Master Chief was choosing which dog to take hunting with him, he asked for the smartest dog they had. The guy selling the dogs thought he would be a troll, and give Master Chief the stupidest dog. He gave Master Chief the Laughing Dog, and the two went hunting. Once Master Chief missed, the dog laughed at him.
For some reason, Laughing Dog was not in Super Duck Hunt. The reason for this is still a mystery today, but recent evidence has turned up that Master Chief may have possibly killed the Laughing Dog. This evidence includes the fact that Master Chief shoots everything he dislikes and the fact that Master Chief was seen burying something in his backyard.