Character is a theif and assassin, so when they are caught by a witness they kill the witness and say : "Dead Men Tell No Tales" Sometimes, depending on the situation: "The Cornered rat, will bite the cat." (When the player is underestimated, and attacked...)
Probably something about A Thousand Bears or A Thousand Animal Bears. It's an inside joke. Or something about toes. Once again, inside joke. But really, I don't know. Usually I just shout something without thinking about it.