Ford Field has never really been known as a tough place to play, mainly because the Lions haven't had much success since it opened and because fans haven't had a lot to cheer about. Although the Lions did sell out every home game at Ford Field up until a few years ago, it was never seen as a tough environment for opposing teams.
On Monday night, that perception changed. The Lions set an attendance record for a home football game at Ford Field (Super Bowl XL still holds the overall football record), and the crowd made so much noise during the game that the Chicago Bears racked up nine total false start penalties. The crowd made it tough on the Bears from the minute their offense took the field, and they had a lot of trouble dealing with the noise, as evidenced by a false start penalty before their first offensive play.
Although it's probably not reasonable to expect the crowd to be this jacked up every week, at the very least Lions fans showed that Ford Field can be a tough place to play. The Bears looked rattled on offense throughout the game, and the crowd played a big part in throwing off any rhythm the Bears tried to generate on offense by causing so many false start penalties.