According to the Detroit Free Press, Ben Affleck and Jennifer Garner crashed a birthday party at Detroit Kid City in Southfield over the weekend. Here comes the ironic part--the event was a Superman-themed party and Affleck (and his wife & son Samuel) are in Detroit because Affleck is currently filming the new 'Batman v Superman: Dawn of Justice' film in the Motor City! You can read more about what happened at the birthday party here.