Answer:
The infamous locking jaw is a myth. The American Pit Bull Terrier and related breeds are physiologically no different from any other breed of dog. All dogs are from the same species and none have locking jaws. There is absolutely no evidence for the existence of any kind of 'locking mechanism' unique to the structure of the jaw and/or teeth of the American Pit Bull Terrier.
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Perfect answer ^^^
Pitbulls and pitbull mixes cannot lock their jaws. It is impossible for any dog to lock their jaws. It is true that pitbulls can bite hard or grip but they can't lock their jaws. I get angry to find out people make a fuss saying pitbulls can lock their jobs. But as you know it is impossible they are dogs not chains or locks!
As i said before the answerr above was perfect. So if you have friends who believe pitbulls can lock their jobs understand you can try but it won't happen.
Reccomendation : Do not try to let a pitbull bite you just to prove the myth.