"You don't see it coming. It plays against type. He's supposed to be a matinee idol, and here you have his own wife" cutting him down to size, Katz says. It's also constructed in a way that can be used over and over in different places, he says.
Keller says the joke "shows a sense of perspective" and reminds people on a subconscious level that Romney, a Mormon, "is not a polygamist, he's been married to the same woman for most of his life, he's good-looking but he puts himself down. It's all there."
Jokes can help neutralize any number of political and personal problems.
One classic was the fake telegram then-senator John F. Kennedy read from his father at the 1958 Gridiron Dinner in Washington: "Don't buy a single vote more than is necessary — I'll be damned if I'm going to pay for a landslide." With that, Kennedy defused allegations that his rich father was trying to buy him the 1960 election.
Reagan scored a similar coup regarding his age, 73, when he ran for re-election in 1984 against Walter Mondale, then 56. "I will not make age an issue of this campaign. I am not going to exploit, for political purposes, my opponent's youth and inexperience," Reagan said during a debate. Mondale laughed and the issue became moot.
This year, Sen. Chris Dodd, D-Conn., is making pre-emptive cracks about his age (63) and late-in-life fatherhood (his daughters are 5 and 2). "I'm probably the only one who gets mailings from AARP and diaper services," he often says.
Obama faces potential wariness about his name. He introduces the topic by describing his first run for office: People everywhere asked, "Where did you get this name, Barack Obama? They'd mispronounce it to me. They would call me Alabama or Yo-Mama, and I'd have to explain it was Obama; my father was from Kenya, from Africa; my mother was from Kansas."
The Mormon faith, with its polygamous past, poses a similar challenge for Romney. He handled it this way at a St. Patrick's Day breakfast in 2005, when he was governor: "I believe marriage should be between a man and a woman … and a woman …and a woman."
Romney hasn't used the joke since then, his campaign says, but Schacter says he should: "I thought it was great. It was unexpected, and it defused some of the tension" about his religion.
Sen. Joseph Biden, D-Del., made short, funny work of a question about his propensity for verbal gaffes and verbosity in general. "Can you reassure voters in this country that you would have the discipline you would need on the world stage?" moderator Brian Williams asked him at an MSNBC debate in April.
"Yes," Biden said. As it became clear that was his entire answer, the audience roared.
Then there's Democrat John Edwards and the $400 haircut, a private expense that was listed on a publicly disclosed campaign-spending report. The former North Carolina senator did damage control last month on NBC's The Tonight Show With Jay Leno. Asked why he and his wife, Elizabeth, eat at Wendy's on their wedding anniversary, Edwards said: "You can't spend money on food when you're spending money on haircuts."
Sometimes humor is the best way to cope with a political problem. Republican John McCain's campaign is hemorrhaging money and staff, but his sense of humor is helping convey resilience. One of his lines from hard times past has new meaning: "In the words of Chairman Mao, it's always darkest before it's totally black."