"using onions to predict weather: Stick an onion outside. Wait 10 minutes. If it's wet, it's raining. If it blows away, it's windy."
"how many words are in the word business studies: First, 'business studies' is not a word; it's two words. Second, there are two words in the word 'business studies'. No, wait ... "
Source: A posting in the
etymology community recommended the website Phrontistery. The website, in turn, provides a link to its maintainer's LJ, 
forthright. Forthright, in turn, on the fourth of January, posted the list, from which these were excerpted. (Note: Most of the keywords aren't nearly as tasteful as the ones I've posted here.) 