Absurd Entries in the OED
Ammon Shea has read the entire OED. He finds some remarkable definitions.
Trondhjemite is defined as ‘Any leucocratic tonalite, esp. one in which the plagioclase is oligoclase’. I have my doubts as to whether anyone has ever thought to themselves ‘I wonder what trondhjemite means?’ But if someone did, and went to look it up in the OED, it seems unlikely that this definition would clear things up much.
He also has a category called, "What were they thinking?" For an example, look up unpoetic.