Strips

ScienceFan's comments are also described by Steven Fry in Quite Interesting (TV show in the UK)

Thanks ScienceFan. And just to back it up, my country's at the equator. And our water in the drain swirls clockwise.

I registered just to post this. The water swirling clockwise North of the Equator is a myth. The Coriolis effect is responsible for large bodies like hurricanes rotating clockwise, the effect is too small to control something as small as the body of water in a drain. Your toilet always drains in the same direction because the jets are angled.