Mike, That is called the chorilais (or however it's spelled) effect. It's the same thing that makes the stuff swing around in the sink. (Or terlet, depending on your point of view at the momemnt.) The bed will spin in one direction here in N. America, and in S. America (or Oz) the bed will spin in the other direction.
Now if you could get smashed on the equater, you wouldn't spin at all, just sink directly to the bottom. Unless your in Panama then your head goes clockwise and your feet counterclockwise. Causing the Pretzel effect. There is no truth to the roomer that the "Twist" was invented by a drunk GI in the Canel Zone, in 1954.
-Fadac (da spinner)