I played a course that has a horseshoe type break in one of the greens. It's a short(er) par-5, so they use to like to cut the hole directly in the middle of the horseshoe of the green. To keep the ball from coming back down to you, you either have to make it (obviously) or put 10 feet past the hole, and the break is big enough that even if you hit the center of the hole when putting from above the hole, it's probably going to be going so fast it won't drop.
If you leave it short, it's coming back 12' or so to you, so that particular hole requires you to run in an uphill, 12+ foot putt. If the hole isn't cut on the break, it can be quite forgiving on your approach though.
If you're left or right of the hole, I don't even know how it's possible to run that putt in.
I said they "Use to like to cut the hole there" because I know the assistant pro at the course, and his brother is a good friend of mine, and they told me, while we were playing it once, that someone took a club or something, and hacked a crude hole somewhere on the green, stabbed the pin into the ground, and made their "own hole" Wanton vandalism is never the answer, but since then, the course no longer puts the hole directly on the ridge. I was told it was put there intentionally to frustrate the golfers though. Watch out for your greenskeepers who are having a bad day I guess.