Bush's Own Version of the Bush Joke

This week at the G8 summit in Japan, George W. Bush wrapped up a meeting on climate change with the words: "Goodbye from the world's biggest polluter."
"He then punched the air while grinning widely," the Telegraph reports, "as the rest of those present including Gordon Brown and Nicholas Sarkozy looked on in shock."
Bush's Napoleon Dynamite moment might have been an effort to laugh off an earlier gaffe: A White House press packet at the G8 had described Italian Prime Minister Silvio Berlusconi as one of "the most controversial leaders in the history of a country known for government corruption and vice." After furor erupted in Rome (Corriere Della Sera called it "a faux pas of unprecedented proportions"), the White House explained, candidly, that an official had simply lifted the passage from the Internet without reading it.
What to make of Bush's humor? Separating out the gaffes and the Bush Jokes, it seems divided between an ascendant strain of ironic-self-mockery and a still-going-strong Wayne & Garth aesthetic. From a recent event with German Chancellor Angela Merkel:

So Bush is a doofus, but why?

One explanation might come from the "incongruity theory" of joking. According to Mary Beard's recent New York Review of Books article on humor studies, the incongruity theory "sees humor and laughter stemming from the inappropriate mixing of categories or registers of meaning." Of course, the theory can't explain why Bush finds the incongruous mix of the German and English "hamburger" funny while most people over the age of 13 don't. But that might be where Freud's "relief theory" of humor can help, drawing a connection between "the bodily release of laughter and the release, by the joke, of inhibited thoughts and feelings." In other words, Bush goes to Europe, feels inhibited (or beset by gaffes), and releases the tension by laughing at anything he can. Hamburger!
Perhaps we should cut the Jester in Chief a break. "Like sex and eating, [laughter] is an absolutely universal human phenomenon, and at the same time something that is highly culturally specific," Beard notes. "It is often hard for the English to share a joke with their neighbors across the Channel." Then again, in Bush's case the whole world chuckled. Just not for the same reason.