In Keith Olbermann's MLBlog, he writes that he remembers hearing the vuvuzela -- or something that looked and sounded a lot like it -- at Yankee Stadium in the late 1960's and early 1970's.
I remember a similar plastic horn being sold at Wrigley Field in that era. There is a comment in Olbermann's post saying the same thing, and others mentioning that these horns were available at Tiger Stadium and Shea Stadium.
Do any of the rest of you remember horns like this at Wrigley? I do.