hat causes normal, worldly adults more low-level social anxiety than all the other worries put together? Tipping, of course. When to do it? How much? Do you tip the petrol pump attendant or is that not allowed? Do you tip your hairdresser and hair washer, or only if the hair washer is hanging around by the till? Do you tip the plumber, if he came out late, even though the bill was eye-watering and he broke the cistern? What about in a hotel? Where do you stop: the cheery waiter, the chambermaid, the concierge? Or do you bung a general tip in an envelope marked "please distribute" and hope for the best? And all this is compounded if you are travelling and in a new country where you are not sure about tipping practices at all.

Every situation is different and just when you think you’ve got it cracked a new one arises (are we tipping Uber drivers now, or only if they give us a bottle of water? If you tip one Uber driver, will all future drivers be able to see?)... and the doubt creeps in all over again.

That’s one level of tipping anxiety (TA). Are we doing the right thing/are we being judged by the people we’re tipping? That’s old-style TA. But now we’re considering the next level up, which is what would happen if your peers, and society in general, were somehow privy to your tipping practices. Would you stand up to scrutiny, or very much not? It’s a timely question because of a recent episode that’s put the wind up Milan’s celebrity community.

A collective of takeaway delivery riders has named and shamed, online, a list of customers, including footballers, actors and TV presenters who allegedly never tip.

According to the riders, they are far more likely to get tipped by low-income households than the rich and famous. And now these rich and famous types are livid and either denying it or, in one case, blaming it on the children.

[How to reach the tipping point for tipping]

If you think about it, this new form of tip-shaming is exquisitely effective. How you tip is a pretty good measure of your generosity of spirit and decency. It’s a small but significant gauge of your general humanity. Some bad people may tip well, but no good people tip badly.

If you were going to tell your children what to look out for in a prospective partner, you could do worse than advise them to check out that person’s tipping policy.

Do they round up (good)? Round down (less good)?

Do they make the effort to go to the hole in the wall to get the cash because they want to be sure the tipee gets it (very good)?

Have they been known to say ‘Haven’t got anything smaller, so, sorry, next time’ (uh oh) or, worst of all, do they not bother to tip at all, even, say a cyclist delivering pizza to their doorstep, at night or during a dust storm (oh dear)?

If that was the case, you would be well within your rights to say to your young adult child, trust me that person is mean to the core. The Milan glitterati know this and they know that coming back from a scandal like this will take some doing.

Mind you, it does make you think. There was the time at the salon when you asked them to split a 20 bill for a tip and then, clocking their expressions, had to pretend you’d meant Dh50. There was the incident when you were caught stealing from the tip left on the table by your husband, because you needed coins for the parking meter. And the time you grossly undertipped the pizza delivery man (after looking desperately around the house for cash and finally having to empty the coin mug).

Tip more and tip lots is the answer. Tip large. We have been warned.