One of the most annoying things that misbehaved students can do is…eat while the teacher is teaching. Few teachers want to be involved in dinner theater when they meant to be teaching. That applies to band and music teachers too.
If you're tired of trying to persuade students to remember and follow your "No Eating in Class" rule, stop the hassle. Post Poster #229 and soon your music or band classroom will be free of French fries and French toast, leaving lots of room for French horns.
Classroom behavior management doesn't have to be such an on-going battle. Make discipline and conduct problems go away by posting Poster #229 and teaching students to remember that they eat lunch only at lunch time, and only outside your classroom.