Ok, this is going back probably way before your time, but the first time I seen a show with a goat chewing on a can was an old "Ma and Pa Kettle" movie. They were made(I think) back in the 40's and showed the life of what would be concidered rednecks nowadays..goats in the house, 12 kids running barefoot and an old outhouse. ( the whole show was based on myths and stereotypes)
And it is a myth that goats eat tin cans..they actually have very touchy stomachs and can die rather quickly if they do eat something like that. My goats were "nibblers" where they chewed up stuff, but didn't actually eat it.