Jaws locking is an urban myth. There is no physical part of any dogs jaw that causes it to lock.
(tyrellsOwl, Mon 28 May 2012, 7:55, 2 replies)

Ridiculously strong jaw-muscles, though

(moon monkey is busy making memories worth repressing, Mon 28 May 2012, 9:41, closed)

This. Bull terriers really don't like to let go of things.

( monster munch person, man, woman... camera... TV?, Mon 28 May 2012, 9:49, closed)

I think there are millions of dog bite victims & hundreds of thousands of vets -
(the latter probably being a subset of the former) who would disagree with you.

Altho there is a wealth of info about this "myth" I challenge you to be able to pries certain dogs jaws apart once they have latched on without having to push their jaws inward and then release by squeezing the sides of their jaws (or shoving your finger up their bum if you are so inclined).
Hindsight - maybe they're all gay (or at least like anal) and they hope for that.
(Misery McUglywife an attention seeking sociopathic fuckstain., Mon 28 May 2012, 9:51, closed)

Strong jaws, that is all. There is no locking mechanism.

Edit: just had a quick google on my phone. Cannot find a single link to confirm its truth. Both reliable and unreliable sources agree it is a myth.
(tyrellsOwl, Mon 28 May 2012, 11:48, closed)

The challenge has been lain down.
...
(Misery McUglywife an attention seeking sociopathic fuckstain., Mon 28 May 2012, 12:03, closed)