Mexican wave

noun
  1. the rippling effect produced when the spectators in successive sections of a sports stadium stand up while raising their arms and then sit down

Word Origin for Mexican wave

C20: so called because it was first demonstrated at the World Cup in Mexico in 1986
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012