Van Halen concerts must have been pretty crazy. They were well before my time, but as a teenager I spent a lot of time trying to master the guitar solo from 'Eruption' on my Gibson SG.
The band's contract for their concerts had an unusual clause: under "Munchies" to be provided for the band, there was a line that read:
M & M's (WARNING: ABSOLUTELY NO BROWN ONES)
Why did they include this peculiar request? Some rumors spread that they were using it to cancel shows on short notice or go on a stage-destroying-spree, but the real reason was something else.
The real reason was that the band was pushing the boundaries of concert productions: elaborate stages, highly technical setups for the equipment, and truckloads of gear. Any errors could have serious consequences: damaged gear, technical issues during the show, or even physical danger to the band members.
They needed a way to quickly check the sophistication of the crew at the venue, so they just looked for the bowl of M&M's on the table. Any brown M&M's and they knew that they needed to double check everything. A canary of sorts.
Here's the excerpt of the explanation from the lead singer of Van Halen, David Lee Roth:
Van Halen was the first band to take huge productions into tertiary, third-level markets. We’d pull up with nine eighteen-wheeler trucks, full of gear, where the standard was three trucks, max. And there were many, many technical errors — whether it was the girders couldn’t support the weight, or the flooring would sink in, or the doors weren’t big enough to move the gear through.
The contract rider read like a version of the Chinese Yellow Pages because there was so much equipment, and so many human beings to make it function. So just as a little test, in the technical aspect of the rider, it would say “Article 148: There will be fifteen amperage voltage sockets at twenty-foot spaces, evenly, providing nineteen amperes …” This kind of thing. And article number 126, in the middle of nowhere, was: “There will be no brown M&M’s in the backstage area, upon pain of forfeiture of the show, with full compensation.”
So, when I would walk backstage, if I saw a brown M&M in that bowl … well, line-check the entire production. Guaranteed you’re going to arrive at a technical error. They didn’t read the contract. Guaranteed you’d run into a problem. Sometimes it would threaten to just destroy the whole show. Something like, literally, life-threatening.
...
The folks in Pueblo, Colorado, at the university, took the contract rather kinda casual. They had one of these new rubberized bouncy basketball floorings in their arena. They hadn’t read the contract, and weren’t sure, really, about the weight of this production; this thing weighed like the business end of a 747.
I came backstage. I found some brown M&M’s, I went into full Shakespearean “What is this before me?” … you know, with the skull in one hand … and promptly trashed the dressing room. Dumped the buffet, kicked a hole in the door, twelve thousand dollars’ worth of fun.
The staging sank through their floor. They didn’t bother to look at the weight requirements or anything, and this sank through their new flooring and did eighty thousand dollars’ worth of damage to the arena floor. The whole thing had to be replaced. It came out in the press that I discovered brown M&M’s and did eighty-five thousand dollars’ worth of damage to the backstage area.
Well, who am I to get in the way of a good rumor?