Stadium Mexican Wave
When at a sporting game, event or music concert in a large stadium, someone stands up and makes their way out of the row to go to the toilet or get a drink. The other people in the row have to stand up and then sit down one after the other to allow the single person to pass by. This creates a mexican wave of people, rather than just their arms. If the rows of seats are long, then the effect is even more enjoyable.
I was at a concert last night and I fancied a beer, but I was in the middle of the row so I caused a Stadium Mexican Wave, it was pretty cool