That's the joke John McCain told in 1986. In front of a crowd at a National League of Cities and Towns convention.
And here's the one he told in 1998: Why is Chelsea Clinton so ugly? Because her father is Janet Reno.
In 2007, he sang Bomb bomb Iran to the tune of The Beach Boys' "Barbara Ann.
In 2008, he said the reason we're exporting so many cigarettes to Iran is to kill them.
You could dismiss all this as the guy just having a misguided sense of humor. But there's that thing about how he voted against a bill that would require insurance companies who cover Viagra to also pay for birth control. And how he can't remember whether or not he's pro-choice. And he's not sure if condoms help prevent the spread of STDs. And the fact that he support Bush's foreign policy, which may lead to bombing Iran.