Relaying this story, Jesse Jarnow tells me that the concept of the "acid flashback" is more urban myth than anything else. Maybe 5% actually experience something, while everything else can just be chalked up to good old-fashioned PTSD.
Whatever you want to call it, my bad trip, combined with the power of 2001, messed me up. A number of times, when I least expected it, I got sucked back into Dave Bowman’s pod. The walls would start doing that shuffle again, sounds going echoey, drifting into a well and then, whammo, it's me, a compressed metal sphere, and, like my mother’s misinterpretation of the movie, I’m being born.
There was the time I rolled up to a party at Rowan University in New Jersey and found myself alone in my friends' car, waiting for a random ride through the Star Gate to subside. The flashbacks hit me smack dab in the middle of one of my college film shoots; luckily it was the very last shot and we were filming in my own room and I kicked everyone out and hid under the covers listening to J.S. Bach. I figured something structured and mathematical would tether me back to the structured universe. It sounds fun, but it was always a hassle.