When The Simpsons went to Australia it was all because Lisa had told Bart that in Australia the water in a toilet spins the opposite way due to the Coriolis effect. Later we discover in the American Embassy in Australia there is a whole contraption built around the toilet to ensure the water spins ‘The correct American way’.
Lisa Simpson was wrong—the amount of water in your toilet is far too small to be significantly influenced by the Coriolis effect.
If the water in your toilet, sink or bath does spin it’s influenced by many other more influential forces than the Coriolis effect.
Phil Plait covered this in more detail while debunking a viral video on his Bad Astronomy blog.