I’ve always thought that it was a send up of an affected northeast country club sort of speech pattern. You know, like the Howells on Gilligan’s Island.
My wife does, in fact, pronounce “vanilla” vanahlla. It makes me laugh just about every time she says the word, which then pisses her off. If there’s baking going on in our house, you can pretty much bet I’m not getting laid that night.
I had to bump up this thread
On the Simpsons tonight (January 31, 2010), Marge and Homer are singing the song “Let’s Call The Whole Thing Off,” and after they’re done Bart says: “Who the hell says ‘pah-tah-toe’”?
I guess the writers of the Simpsons read these forums
Actually (possibly inspired by this thread), I mentioned this to my dad recently, and he said that when he was a boy (20 years after the song was written), it was an occasionally heard upper class pronunciation.
I occasionally pronounce it “Pah-Tah-Toe,” if I am not consciously thinking about what I am saying. I have to remember that there are certain words that sound funny if the long “a” is not used. At least people understand when I say “Pah-Tah-Toe,” it is when I talk about those big cyclones called “Tor-Nah-Does” where they start to look confused.
Christopher Walken (IIRC) once did a funny rendition of the song on SNL, where he sang both words the same way: “You say tomay-to and I say tomay-to, you say potay-to and I say potay-to”, etc. and didn’t quite understand when people tried to explain the “correct” pronunciation.