Phrase borrowed (more or less) from TV's "Wheel of Fortune", indicating
disrespect for someone's mental abilities. Since generally the contestants on
Wheel aren't exactly Einstein, telling someone to buy a fucking vowel is about equivalent to "Get a clue, moron!"
You think the War on
Drugs is working? Buy a fucking vowel!
President
Bush wants to
help the middle class, eh? Maybe he should buy a fucking vowel with his family fortune.