It's time then for a true story, yeah?
I was fishing for half an hour for the Rusty Prison Key (why isn't that an achievement, eh?) and was about to throw out my last line. Obviously I only caught a Shimmering Minnow. So sneakily I cast once more and saying out loud, "I'm not gonna reel this one in so it could as well be the key, ya know." And of course, it was the key! Shame it's only rubbish coming out of that locker.