I don’t always Google my cold symptoms but when I do I have the Black Death, pregnancy and a disease only horses get.

This is not actually that surprising. I’ve had every disease known to man, except hypochondria, and I’ll probably get that from a toilet seat later today.

But I will admit that some diseases are definitely all in the mind. There’s a sign hanging from the ceiling at a hospital near where this columnist lives: “Beware of your head.” Wise advice.

Consider a letter I received from a reader in Thailand about a murder earlier this year. A man was found dead in Chiang Mai with 15 bullets carefully fired into his bottom. Investigators, puzzled by the mode of execution, eventually uncovered one of those bizarre-but-true stories that you only get in Asia.

A woman, 39, had been seeking a cure for the constipation suffered by her husband, 40. As one would, they consulted a witchdoctor, who confirmed that a “Death By Constipation” curse existed, but a spell to remove it could be had for the equivalent of $2,900.

So far, so relatively normal (for Asia). But later, the couple remembered that a family member had died of constipation 10 years earlier. OMG!

Clearly, the doctor was a serial killer whose modus operandi was to remotely shut down people’s digestive systems!

So the couple did what they felt they had to do, according to police: They got a gunman to kill the witchdoctor by gunshots to the buttocks because — if you think about it scientifically — that would surely break the spell, right?

Last I heard the couple were facing the terrifying prospect of many years in Thai jail, a thought I know will dramatically cure the husband’s constipation. Stand well back!

Constipation is just one of many ailments with a mental element. I once told a colleague that his bloodshot eyes were “a sign of a twisted uterus” and he took it seriously, rubbing his abdomen and making an appointment with his doctor.

Which reminds me: we are overdue for an outbreak of koro.

This is a disease that appears in epidemic form every decade or so. It goes like this. 1) A guy imagines his genitals are smaller than he thought and privately tells a friend that they’ve shrunk. 2) The friend starts to worry which causes his genitals to shrink too. 3) Repeat x 1,000.

There’ve been many koro epidemics (Singapore in 1967, Thailand in the 1970s, Northeast India in the 1980s, West Africa in the 1990s and 2000s) but except for a small 2010 outbreak in south India, nothing recently. I may start an outbreak myself. Male readers: Do you feel your boxer shorts are more roomy than they used to be? Uh-oh.

The official modern medical treatment for koro is “education and reassurance”, but I suspect the traditional Chinese remedy works better: Healers bang a giant gong very loudly near the sufferer and tell him he’s fine now.

In fact, the big gong thing could pretty much cure anyone of anything, including constipation. I may wheel one into my local hospital and try it out for the sake of medical science. Stand well back!