I have dim recollections of singing something like this at Guide camp - every line was followed by - Oo-oo-oo-oo Aa-aa-aa-aa- and the song finished with a very loud "Gotcha!" (and probably a few screams from the youngest ones who hadn't heard it before! Sorry I can't remember more. There's also the less gory one "There's a long long worm acrawling along the roof of my tent" Tattie B