From The New York Times to Fox News to your very own dinner table, people across the country and across the ideological spectrum have been making the Osama/Obama mistake: accidentally saying "Obama" instead of "Osama." At first it was confusing—receiving a text message on Sunday night that read "Obama is dead!" elicited a reaction very different from the alternative. But now it's just a big, embarrassing joke. See video montage below:

But maybe it's not so embarrassing. We spoke with University of Pennsylvania linguistics professor Mark Liberman, who explained why the two names are so easily confused. Obviously, the words differ by a mere letter and have very similar pronunciations, which definitely contributes to the confusion, but the mix-up actually happens so often for a different reason: the syntactic category rule.

The syntactic category rule means that when two words are confused for one another the "target" (the word replaced) and the substituting word are almost always of the same syntactic category. In normal speak: nouns replace nouns, verbs replace verbs, and so on. If "Obama" were a verb instead of a noun (as in, the Democrats are going to Obama the GOP in 2012), we would be substantially less likely to confuse it with the noun "Osama."

Of course the gaffe doesn't just happen because both words are of the same part of speech. The speaker is also subject to what linguists call "priming." Your brain makes certain words more accessible to your tongue when they resemble--in pronunciation, in meaning, in subject matter--words that you frequently hear. "Priming means that when you've been reading/hearing/thinking about hospitals, words like 'doctor' and 'nurse' will be recognized more quickly, and are also more likely to be substituted in a slip of the tongue," Liberman explains. So hearing Osama and Obama in the same context makes your brain more apt to use them interchangeably in speech. "Normally this is a good thing for communication," Liberman adds, "because it takes less effort to think of primed words."

For those who suggest that some pundits have made the slip because maybe they wished death upon Obama instead of Osama, it's more likely that these slip-ups are related to the priming phenomenon--call it linguistic laziness--rather than contempt. As Liberman puts it, "Obviously, 'Osama' and 'Obama' are very similar in sound and spelling, and both are proper names of men prominently involved in recent events. So this is, so to speak, a textbook case."