I have them all the time. When I was actively working on lucid dreaming / dream yoga, I was particularly attuned to them (as the practice necessitates.) The most common instance is when one sees something in one’s environs that one has never noticed before. It would happen all the time when I was living in Bangalore because it was such a visually chaotic and rapidly changing place that I could walk down a street ten times and not notice an unusual sign or building facade, and then — POW! — the moment I saw it I was in utter disbelief that it could have been their all the time.
I haven’t discounted (nor accepted) the simulation hypothesis, and I suspect whatever the world is, it’s not precisely any of the things we’ve thought it to be.
Tiger Riding for Beginners 