In their prime, Van Hallen put on massive and complex light shows at their concerts. They had complicated stage equipment and their contracts with the arenas they played in on each tour stated very specific requirements. To help them see how well their technical specifications were followed, they added a clause that no brown M&Ms should appear in their dressing room. It was an easy way to test if the entire contract had been read. Upon entering the dressing room, they’d know instantly that they should check every detail of their tech requirements.