Making someone laugh is an aggressive act: you're quite literally altering their breathing pattern. It requires a certain sharpness, a distinct edge.
I thought about this as I surveyed the current state of humour in the now-unfolding presidential campaign. Neither one of the major candidates, Barack Obama or Mitt Romney, is much of a funnyman.
It's not surprising. A few years ago, a Republican presidential candidate called me. He was appearing the next night on a late-night talk show and he needed help.
"Can you tell me what to say? Something funny," he said. "Some humorous patter or something?"
"You want me to give you some jokes to tell?" I asked.
"Yeah," he said, "jokes, or just some funny amusing 'takes' on whatever."
"OK," I said, "here's a funny one." And I then proceeded to tell him a fairly racy joke involving the Pope, a policeman and zoo keeper.
"Wait a minute," the candidate interrupted. "I can't tell that one."
"You can't?" I asked.
"I can't," he said.
"Are you sure?" I asked again. "I mean, it's a pretty funny joke. See, when the Pope and the zookeeper get thrown in jail..."
"I really don't want to hear it. Don't you have any funny patter that you can give me about the events of the day? About the budget crisis or something?"
I had to admit that I didn't. In the first place, I'm not much of a joke writer. What I do, mostly, is write comic dialogue for actors. Which, I'm the first to admit, is a lot easier.
I couldn't really help the candidate. He wanted jokes. But for someone who is not a natural comedian - or, frankly, very funny at all - jokes can be dangerous things. It's always baffled me why politicians, most of whom are stiff and terrified about saying something weird or off-putting, would want to take the risk of telling a memorised joke. Why not just aim for an affable blandness, which is so much safer?
The only real benefit to being a presidential candidate is that you're awarded instant amateur celebrity status, sort of like singing in a television talent contest. Nobody expects you to be very good - to sing very well, to tell a joke with the right sense of timing, or even to be very comfortable on the chat-show set with Jay Leno or David Letterman. What they expect you to be is real. And everyone, with the possible exception of Mitt Romney, can manage that.
I tried to make my case to the candidate: don't try to deliver scripted jokes. Just be relaxed and pleasant. You're a Republican, I told him. You came into this world with certain immutable deficiencies.
"So what do you think?" I asked, as I wrapped it up with the candidate. "I have to tell you, that I've been in the television and media business for a long time, and I've been active in Republican politics for almost as long, and I'm convinced that this is a winning media strategy."
There was a silence on the phone.
"So no jokes?" the candidate asked. "But I'm supposed to do a late-night chat show tomorrow."
"Sir," I said, "they pay the host of that show $14million dollars a year to be funny, to keep the show moving, and to guide the conversation. Let him do it. You just sit there and be yourself."
"But what if he asks something embarrassing? Shouldn't I have a zinger ready?"
"A what?" I asked. "A zinger. It's a show business term. It means -"
"I know what a 'zinger' is. Look, if he says something that embarrasses you, say 'Boy, that's embarrassing'. My advice is to sit there, try to have a good time, and do your best to act like a human being."
"Act like a human being," he repeated dubiously. "OK," he sighed. "I guess I'll try it."
Just before he hung up, he asked a final question. "What's the rest of that joke? The one about the Pope and the zoo keeper?"
I told him. He didn't laugh.
"You know, sir," I said, "political correctness and other sensitivities aside, that's a pretty funny joke. A human being would have laughed."
"Yeah, well, a human being doesn't have to run for president."
Rob Long is a writer and producer based in Hollywood
On Twitter: @rbcl