For me is the big Octorock of JabuJabu's belly on OoT, just because after all this years, I don't know how to legitimately hurt that thing!!
Seriously, I hit him with the boomerang and I don't have time to hit it's weak point. I tryed alot of things and nope.
I just get to hit him with some luck, and when he hits me turns around and then I hit him with the boomerang to hit it's weak point. Seriously that's what I do when playing OoT agaist that mini-Boss. (Still could've looked a guide to see how to legitimately hurt him... But eh~ too lazy I guess. And the fact that I beated the game more than 5 or so times, so who cares...)