Problem-Remind people that Leffe is a highly desirable, premium beer which rivals Champagne.
Solution-Show people that champagne is used for special events in order to save the Leffe for something more important.
Insight-At celebrations, champagne is wasted as a mark of lavish importance. The Leffe is saved as it's too important and decadent to be wasted frivolously. As during the French revolution production of Leffe stopped.
Idea-Print ads which display this sentiment in an amusing manner. Social media and PR stunts can back up the campaign asking fans to share their ideas on what better ways Leffe can be enjoyed.