I have nothing as interesting as the stories here, though there have been a couple instances of my dreams sabotaging my attempts at lucidity by throwing lots of rapid-fire realistic events at me.

The more disturbing one, and more recent, involved all my priors actually making sense, except the one I wanted to test: a dead relative had come over and was acting completely normal. As soon as I tried to do a reality-check, she came to talk to me. She gave me a card that I was ready to put to the "changing text" test, but was distracted again before I could do so. It was also bothersomely realistic in terms of physical sensations, so I had a very hard time convincing myself that it must be a dream on the grounds of my memory insisting that this person was dead. (I spent some effort before that reminding myself in various dreams that "if you're wondering, it's almost definitely a dream", which I thought about asserting before I got swept up in the distractions).

Could be my mind subconsciously self-sabotaging, which is considerably more disturbing than the dream (but wouldn't be too surprising).