I first heard “off the hook” meaning “totally wild” or “out of control (in a good way)” a few years ago. (Example: “We’re hiring bellydancers and fire jugglers for the party – it’s going to be off the hook.”)
Like so much innovative American language, it seemed to arise from the African-American community. But it puzzled me, since “off the hook” already means something else, along the lines of “no longer responsible for” as in, “I did the dishes, so you’re off the hook.”
I wonder if the etymology of this (new) expression has something to do with the idea of a meter (like something showing dBs) rocketing so high so quickly that it flies off its “hook”? That’s just a guess. If anyone has the actual source of the term, I’d love to hear it.