Back in the day (that's the 80s by the way), the Music Industry got pretty rattled by the rise of the compact cassette. They ran a campaign to "inform" the public that not only was copying music to tape illegal, but it was also harmful to the record company's profit margins.
This T-shirt from Force 18 is a replica of the old image and slogan used by the Record Industry - "Home Taping is Killing Music"