I think it's Wikipedia because "walkman" has a much longer history as a brand name, from cassette players to cell phones.
I remember times where back where I lived "walkman" was a plain noun meaning "any kind of portable cassette player".
I remember times where back where I lived "walkman" was a plain noun meaning "any kind of portable cassette player".
http://en.wikipedia.org/wiki/Duct_tape#Etymology
Duck Tape is trademarked, but it's possible that was the original term for it. It's weird.
I don't appreciate the downvote.