i think it's supposed to be an oxymoron, like "clear as mud"

by Anonymous 13 years ago

except "clear as mud" means something is unclear while "clean as whistle" actually means something is clean. I think It's because whistles are traditionally very shiny and polished.

by Anonymous 13 years ago

well when ever i've heard the saying "clear as mud" it's been said as a question to me, as in... "do you get it?" and it's always been when i understand it...

by Anonymous 13 years ago

clear as mud http://www.usingenglish.com/reference/idioms/clear+as+mud.html clean as a whistle origins http://www.phrases.org.uk/bulletin_board/33/messages/522.html

by Anonymous 13 years ago