The closest I've ever been to a flash mob type of situation was sitting at the Dub on a Sunday afternoon before St. Patrick's Day. (In the Boston vicinity St. Patty's Day is a HUGE deal.) S and I were sitting there minding our own business when an entire bagpipe and drum band (complete with step dancers) start funneling in with 75 of their closest friends. We were treated to a jig or two before they ordered all the Guinness that was on tap.
Today I was in need of some cheer. I found that cheer in the form of a musical flash mob performance of one of my all time favorite holiday songs. Just watch and you'll see.
How brave was that first girl? You have to have guts to look crazysauce for 10 whole seconds before people realize what is happening.