The Coriolis effect is probably the most scientific excuse humans have for staring into toilet bowls. This effect makes objects on the earth curve when they should go straight, and it's why some people insist that the throne drains in the opposite direction in the southern hemisphere.
If you've taken a plunge down to Australia and given this a try, you've probably been disappointed. Every John has angled jets that pass water into the loo to drive the direction of draining water. The design of the dunny is more powerful than the Coriolis effect in such a small body of water.
On Earth, an object that moves along a north-south path will appear to veer to the right in the northern hemisphere but to the left in the southern hemisphere. There are two reasons for this phenomenon: first, the Earth rotates eastward; second, the relative speed and direction of a point on earth is a function of latitude. For example, if you were to fire a ball from a cannon northward from a point on the equator, the ball would land to the east of its due north path. and the southern hemisphere would be the opposite.
The Coriolis force works on air and water in a similar fashion but only if the volumes of these fluids are extremely large, like low pressure or high pressure. In the northern hemisphere, low pressure turns counterclockwise with high pressure rotating clockwise. In the southern hemisphere, lows spin clockwise and highs spin counterclockwise.