This is a rock 'n' roll legend that actually happens to be true. In the 1980s, rock band Van Halen famously banned brown M&M's from their dressing room – but rather than being a sign of diva behaviour, it was a clever way to ensure safety and attention to detail on tour. Van Halen's productions were massive and technically complex, and the brown M&M's clause acted as a hidden test: if the crew overlooked this small detail, it indicated that they might have missed more critical safety requirements.