I'm just going to take a wild guess based on BryanP's last post, so, if you avoided the spoilar warning, don't read this!
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What did they do? Bite their tongues off? I'm guess from the title that the third guy was relieved of his mouth, though, I don't see how removing his mouth made him immortal, maybe there was something more to it.
It takes a lot of determination to bite off one's tongue...I suppose they'd have it. >_>