People are weird. I used to know this guy whose favorite pastime was lying. Just like you or I might pass a free hour with a common hobby such as reading, watching TV, or weaving one’s forearm hairs into tiny images of first century Roman proconsuls, he filled his spare hours thinking up malicious fictions about his friends (the fastest shrinking group of people in the world, with the possible exception of the "I Love AIG" group on Facebook).

But liars inevitably trip up. People would confront him, saying (for example): "You said I was attending a carrot-users addiction clinic, but it’s not true."

"What?" he’d sneer, feigning outrage. "You can’t take a joke?"

Despite his obnoxiousness, I kept my friendship with him on exactly the same level as my relationships with other buddies, except for the fact I hated him and wanted him killed, very slowly indeed.

But I realized he’d taught me a lesson: actually, two. First, I used to be against the death penalty because it was too cruel. Then I was opposed because it wasn’t cruel enough. He needed to suffer for eons.

The second thing he taught me was that jokes are defined by the listener, not the speaker. A joke isn’t a joke if the audience doesn’t laugh. (Which is why columnist Chip Tsao, who tried to joke about domestic helpers, had to apologize.)

Top British comedian Billy Connolly once made a joke about a hostage threatened with beheading in Iraq. Fed up with the mass TV coverage of the event, he said, at a live show: "Wish they’d get on with it!" No one laughed. The humor quotient went into steeply negative territory when they did cut the guy’s head off. Connolly no doubt felt like cutting one of his own favourite organs off as penance.

In contrast, pop singer Bono once stood on a stage and clapped his hands slowly. "Every time I clap my hands, someone in Africa dies," he said.

Someone in the crowd shouted out: "Stop clapping your hands, then."

Now THAT was funny, and indicates this principle also works the other way round. If someone makes a completely sincere statement, but the audience roars with laughter, a certifiable act of humor has been committed, albeit accidentally.

For example, Arnold Schwarzenegger made me chuckle when he gave the conservative view on a hot current issue, saying:

"Gay marriage is something that should be between a man and a woman."

One of the best accidental jokes came from a Hong Kong newspaper that printed the following correction:

"In yesterday’s newspaper, we referred to a unit of the police force as `uninformed detectives.’ This was an editing error. It should have been `uniformed defectives."’

I was told by a former police officer that "uninformed defectives" would have been most accurate.

And we can give thanks to Donald Rumsfeld, former shooter-in-chief of the US administration, who uttered the following words:

"Reports that say something hasn’t happened are always interesting to me, because as we know, there are known knowns. There are things we know we know. We also know there are known unknowns. That is to say, we know there are some things we do not know. But there are also unknown unknowns: the ones we don’t know we don’t know."

Anyway, the cruel "joker" mentioned at the beginning of this column ended up friendless, jobless and homeless.

Which isn’t funny at all.

Heh, heh, heh, heh.