The Coriolis Effect causes tornadoes, hurricanes, flushing toilets etc. to rotate counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere.
More on the Coriolis force:
http://en.wikipedia.org/wiki/Coriolis_effect http://abyss.uoregon.edu/~js/glossary/coriolis_effect.htmlWith a flat earth, if the flat disk is spinning, the Coriolis effect would cause all these things to spin in the same direction. The only way to make hurricanes in the Southern hemisphere spin clockwise with a flat earth is if the Southern hemisphere were rotating the opposite direction of the Northern hemisphere. If this were the case, there would be obvious evidence (there isn't).
This brings us to 2 possible conclusions:
1. Every single hurricane, tornado, toilet and wind current since the dawn of time is part of the Conspiracy.
2. Earth is round.
If you choose the former, be prepared to explain how inanimate objects were convinced to join the conspiracy.