For me, only once, maybe, and it was in a dream.
I was in a world made all of paper. I was made of paper. I was wandering around a bit examining this strange place, and hoping nobody came up who needed to write a note, when I found myself near a spinning vortex, like a whirlpool of paper all flowing around in a circle and draining down and away. Something in me clicked with recognition, and just as I was thinking "wait... wait... I know this place" I found myself being sucked down into the vortex.
I fell for what seemed like forever, and as I fell I picked up speed, but never reached a bottom. It was just like the whole of existence was blacking out as I fell faster and faster, and time as well as space ceasing to exist.
Then in the midst of the deepening darkness, I was touched, and pulled forth, and back into the room where my body was, awake, and thankfully a biological human again. A voice said quite clearly "Now, boy, it's time you meet your maker" -- which is all it said although I thought I picked up the thought "and don't do that again" at which a brilliant dot of light winked into existence at the very core of me, where you think you are when you try to pinpoint where your consciousness is. It was there, just there, within me no matter how closely I tried to look at it, it was within where I was looking from and still I somehow saw it, and how bright and clear and in focus it was I cannot even describe.
It was just a point, and it vibrated and rotated and split into a line, then the line vibrated and rotated and split into two perpendicular lines, then three, then four, then an infinity, each as bright as the dot and yet of no thickness whatsoever. As the lines split they divided space, cutting first my left off from my right then my top from my bottom then my past from my future, and more into dimensions I cannot even imagine, but saw as it happened somehow. I was somehow in the middle of all the chunks of myself that the light divided, watching my parts cleanly separated from each other by the infinite dimensional light drifting off and away from each other in amazement. I remember thinking "this can't be happening but it is".
So was it God? If it wasn't I can't imagine what else. Not that it really had said much to me, but I guess it saved me.