Casey Kasem’s greatest hit: Negativland and “the letter U and the numeral 2”

The death of Casey Kasem on Sunday reminded different people of different things, from those long-distance dedications on “American Top 40” to his iconic voicing of Shaggy on “Scooby-Doo, Where Are You!” But for some of us, Kasem’s greatest achievement was his most unintentional.