I always liked this song.
The words originated from an article written in the Chicago Tribune by Mary Schmich in 1997. It had the title of: "Advice, like youth, probably just wasted on the young"
Soon an urban legend rose which attributed the text to a commencement speech by Kurt Vonnegut, the author famous for his novel "Slaughterhouse-five" published in 1969. He never made a commencement speech, but said he'd have been proud of this one had he made it. For a long time his lawyer was inundated with requests for copies of the text.