One way to hold bonkers: picture the second right after a light knock on the head. Nothing lines up. The person says odd things, does odd things, and everyone around them laughs rather than worries. The dictionaries only guess at this history, so keep the picture as a memory hook, not a fact. It still ties the word together. One use names whoever or whatever has landed in that state: a person, a plan, a price. The other names the thing that keeps knocking until you get there.