My favourite example comes from around ten years ago when I told a class, several classes in fact, that the only really good question is one that can't be answered. I'm not quite sure what I meant, but it sounded good. Quite by accident I discovered that one very bright student incorporated this apercu into a speech, telling the world that Mr Connor had told everyone that the only really good question is one that has an answer. I wasn't really all that miffed as I quite liked the sound of that - and began to offer it occasionally in lessons, immediately following a lesson in which my original comment had been let loose for contemplation.
Marking essays, of course, provides a wonderful window onto the capacity of the mind to distort any in-coming data in weird and woeful ways. Except once you come to accept this the woe sort of evaporates to be replaced by a wary respect for the wrongheadedness central to our species. If nothing else it's highly entertaining once you get beyond the anguish of failing to connect. And there's something endearing about people only hearing what they want to hear.