I missed out on the 60s, but I remember my older siblings talking about music albums that "blew their minds" or certain pharmaceuticals that were "mind blowing". I remember thinking that idea sounded pretty good to me. I looked forward to my first mind-blowing experience. I think it was the first time I saw the movie Star Wars. I couldn't believe a movie could look like that, with real lasers and big explosions and space ships. It truly blew my twelve year old mind.
Of course, other things have blown my mind since then. I thought Pink Floyd's concept album "The Wall" was mind-blowing, since no other group was using all of those sound effects and orchestras and choirs to make great music like that. I also thought the cult TV series "Twin Peaks" was mind-blowing, because the director and cast weren't trying to tell a logical story in a linear way. I was blown away by the first season's episodes.