I'll say the 10-30-2011 game where the Rams beat the Saints 31-21 at The Dome. Before that game, the Saints were 5-2. The Rams were 0-6. It was right after the St Louis Cardinals had won the World Series and the team was in the house and on the field with their WS trophy. Not sure if they brought their mojo along with them or what but it was a shocker of a win. 'Course the Rams only had one more win that year but THAT win was a big one because it was totally unexpected.