I was just listening to BBC Radio 4's Loose Ends earlier when I heard an interview with Gavin Pretor-Pinney. Part of it discussed the phenomenon of Mexican waves in the northern hemisphere of the world travelling clockwise around a stadium, and southern hemisphere waves travelling anti-clockwise which he observed by looking at online videos of Mexican waves from around the world. There was some joking about this, but he did observe it to some level, and I'm wondering why. Do people in the southern hemisphere tend to 'think' more anti-clockwise rather than clockwise? If this were generally proved, I might theorise it comes from spending a lifetime seeing the water go down the plughole in that direction, and given children's fascination with watching such things happen from a very early age, it might embedded within the collective mindset of a crowd. I wonder what happens if England play South Africa, do two Mexican waves travelling in opposite directions meet?