When you pose for pictures with short friends, you hunch over so you don't tower above them — you scrunch up your shoulders, bend your knees, and try to look smaller.
You can also have a hunch, which has nothing to do with scrunching. When you have a hunch about something, you think it might be true. Your dog bolts over the fence, and you have a hunch he's heading for the neighbor who feeds him pâté. Hunch is an odd word of unknown origin, which seems to have originally meant "to push or shove" — to nudge.