...came out of the mouth of Jay Leno.
Yes, kids, I know this is difficult to believe, but Jay Leno was once a reliably funny, hard-working standup comedian. Really. My fingers aren't crossed while I'm typing this, honest.
This all changed the moment that Johnny Carson retired; upon becoming the permanent Tonight Show host, Leno and his writers became relentlessly lazy, lowbrow, and conservative. And of course by now l'affaire de Conan has stripped any remaining feathers of Leno's dignity, not that there were many left after 1992's l'affaire de Letterman and nearly two decades of being terminally unfunny on a nightly basis.
Nevertheless, before 1992 (and by some accounts, even till this day when he makes unannounced appearances in comedy clubs), Leno was, at least to me, pretty funny. And this joke is from those days.
In the aftermath of the 1986 Chernobyl nuclear disaster, which before what's happening in Japan right now was the worst nuclear accident in history, Leno made an appearance on... well, I'm not sure if it was Late Night with David Letterman or Carson's Tonight Show, though I'm leaning Letterman. In my memory, he didn't tell this joke as part of a standup routine but on the couch, talking to the host. The screenshot above may even capture him in the midst of telling this joke.
Anyway, this is strictly from memory, and thus paraphrased and subject to the inaccuracies that twenty-five years have inflicted on my brain. But, to the best of my recollection, here it is. It is a joke that Leno wouldn't dare attempt now, at least in front of cameras:
Every time there's a nuclear accident, the nuclear industry always gets some expert to go on TV and say "nuclear power is safer than crossing the street." Well, all I know is that if I get hit by a bus in Philadelphia, they don't make people in Sweden stop selling vegetables.
And that, kids, is all you really need to know about nuclear power.