Van Halen and Brown M&Ms

via thesmokinggun.com

According to David Lee Roth, this was listed in the technical portion of the contract not because the band wanted to make capricious demands of the venue, but rather as a test of whether the venue had actually read and honored the terms of the contract, as it contained other requirements involving legitimate safety concerns.

The band developed the M&M's demand as a means of checking whether the venue was properly honoring the terms of the contract to their satisfaction. Subsequently, if the bowl was missing, or if there were brown M&M's present, they had reason to suspect that the venue might not have honored legitimate technical and safety concerns within the contract. As a result, the band would be within their rights to inspect the technical side of the performance prior to going on stage, and/or request the venue redo their work properly.