Great photo. 
During the storm, i was locked out of Cuatro Vientos and heading home. We were at the bus stop, waiting, and the rain came and the lightning came and we quickly got out our ponchos (which we had saved from Sydney08) to keep dry. There was another group with us, and the huddled under the bus stop, while the people in our group stood in front of them, to protect them from the rain.  They had fun in the rain, but were disappointed when the other group didn't even say thank you for being a barrier. They might not have been aware that's what they were doing. 
But definitely one of those WYD things that will always be talked about.