This article is from the Pratchett Newsgroups FAQ, by Orin Thomas email@example.com with numerous contributions by others.
The words to the Hedgehog song (many different versions) can be found
at the Pratchett Archives. Download, Print, Visit the pub, consume
alcohol and sing. (It probably sounds better)(Well .. to you at least)
There is no line about a two speed hedge trimmer in this song.