It’s been well over a decade since the last time I got high, but for me personally it was like the pattern-recognition portion of my mind would go into overdrive and start making all sorts of connections that just weren’t there. Scribbles on a page would be the beginnings of a beautiful landscape or figure drawing. A song lyric might suddenly be a commentary on my entire life or life and the universe as a whole. A small throwaway line in a movie might suddenly put everything else that’s happened into question. In some cases this was an amazing thing to have because you’d make connections you might not have normally, but unless you wrote it down, those connections were lost or meaningless by the time you came down. And even if you did write it down, it still might be meaningless.
In my case though, it often lead to a lot of paranoia, as scenarios I would imagine in my head might sound just as real in my head as if they were actually happening. I remember one time I was in our basement, I heard a SWAT team bust down the door into my house and everyone charging to the basement door screaming, “He’s down there! He’s down there!” Then… silence. A few moments/minutes later, the door slowly creaked open and one of our cats came down. My heart was pounding out of my chest. I finally got the courage to go upstairs and look, there was nobody there, door was fine, nothing.