If you saw the 1992 movie Chaplin, you heard Charlie Chaplin (played by Robert Downey, Jr.) refer to his suit as a “whistle” and explain that whistle and flute rhymes with suit. That’s (old-time) Cockney rhyming slang, a slang style originally limited to the Cockney English dialect of working-class people in London’s East End. (The character Eliza Doolittle of My Fair Lady was a Cockney speaker, but I don’t know if she used rhyming slang.)
Celebrities are also used in rhyming slang and the new book Shame about the Boat Race: Guide to Rhyming Slang from Collins (ISBN 0007241135) gives examples of modern celebrities finding their way into the lingo. The title refers to “Nice legs shame about the face” (metro.co.uk/news/article.html?in_article_id=23975&in_page_id=34) [EDIT (5/30/10): dead link] turned into rhyming slang.
Assuming the expressions are common enough to be shortened, some people might drink too many Britneys (Britney Spears rhymes with beer) and then Wallace (Wallace and Gromit rhymes with vomit).
We’ll have to see if any of these become ordinary words like giving someone a “raspberry” (making a derisive breaking-wind noise with your mouth on your hand, also called a Bronx cheer). Raspberry tart rhymes with fart.
See also: Web’s Greatest Dick’n’arry of Cockney Rhyming Slang