Lua error: Internal error: The interpreter exited with status 126. The most common way to do this trick begins with rolling Fakie. Place your feet in the same position as you would a Heelside Railstand. Then while rolling Fakie, wind up as if you were going to do a Backside Kickturn, but instead enter a Heelside Railstand, but don't put your front foot on the front wheel. Keep your front foot against the Griptape and push the board around 180 degrees in the Railstand. Then once the board has finished rotating, nudge the board back down onto the wheels and roll forward out of the trick.
The Casper Disaster is commonly believed to have originated from a 180 Casper gone wrong. If you attempt to do a 180 Casper, but do not put your back foot far back enough, you will get a Casper Disaster instead of a Casper. The origins of this theory haven't been verified, but the name of the trick seems to speak for itself.