"You're pregnant!" No. I'm not.

I jumped in a taxi the other day after a TV appearance in the city. I thought I’d scrubbed up pretty well until the cabbie said, “You’re having a girl!”

“Sorry?’ I said with confusion.

“You’re having a girl, “he said with a huge confident grin.

“Actually I have three boys,” I said, still not understanding where he was going.

And then he dropped the clanger. “You’re pregnant, right?”

“Uh.. no.”

He suddenly looked panic stricken and turned a shade of violet before being saved by a call on his mobile phone.

I was more amused than upset, as I have never been fitter. So what little bump or shadow gave him the confidence to go THERE? To the place of no return. To the place that could easily land you with a slap on the face?

It’s a place visited too often by well meaning, intelligent men, who have never been taught the most basic of social rules. Never utter these five words. “When is the baby due?”

The only exception to this rule is if the woman appears to be going into labour.

Ignore all urges to comment on her tummy, even if she’s as round as a barrel, unless she’s told you directly or you’ve seen a stick with two blue lines.

You see, suggesting a woman is pregnant when she is not, is confidence crushing for her. Long after you forget your shameful question, she will still be thinking about it; when she looks in the mirror, when she pops on her new dress, when she catches a glimpse of herself in the reflection of a shop window.

There’s a fair chance she will find new girlfriends with the names Nancy Gantz and Spanx. And she will repeat the tale to other women who will gasp in shock, tell her it’s outrageous and lie about what a flat tummy she has.

The pregnant pause tops the list of horrifying social faux pas. Ahead of “Did you finally break up with that loser? (No I married him), trying to wipe something off someone’s face only to discover it’s a mole, or calling out someone else’s name in the throes of passion.

I witnessed my first false pregnancy showdown lining up to enroll at University one year. A guy in the queue said to the girl in front of me, “So when are you expecting?”

“Expecting what?” She replied.

“The baby.”

A hushed silence fell over the crowd. Just like a car crash we couldn’t avert our eyes, even though we knew it was going to end up badly.

She handled it brilliantly.

“I’m not pregnant. I’m just fat!”

“Ooh,” he said, sounding like someone had just winded him. I’m guessing he hasn’t made the same mistake again.

Plenty of guys do. Like a repeat offender mate of mine who should have known better but couldn’t resist asking a waitress, “When’s the baby due?”

She was so upset she refused to serve his table again.

Of course men aren’t alone when it comes to making the mother of all mistakes. Two of my girlfriends with small babies have recently been congratulated on their pregnancy and asked for a due date by a woman.

It’s even more crushing coming from a member of our own tribe who should know the female body a bit better and who should know the consequences of bad baby judgment.

So, if you’re ever tempted to broach the subject do yourself a favour and remember, mum’s the word.

Have you ever found yourself having to reply to this question? Ever asked it yourself?