"Can you tell me how much you earn?"
It's not a question many of us would be happy asking a colleague, around the boardroom table or in the queue for the work canteen.
It's not a question many of us would be happy answering either, according to campaigners for women's rights.
But it's time for us all to be much more transparent about our salaries, in order to end a "culture of pay secrecy", the Fawcett Society says, if we want to address pay inequality.
A survey on behalf of the Fawcett Society found 61% of us are "uncomfortable" at the idea of asking others about their pay. Moreover, half of us wouldn't be happy to reveal our salary details either.
But sharing more information about what we earn may be the best way to ensure that women are in a position to argue for fairer treatment over pay, say campaigners.
They point to the example of Kay Collins, a chef, who discovered that a male chef in her kitchen was being paid more than her.
She says the initial conversation wasn't awkward at all: "We were working together. It was a quiet day. My colleague Chris was leafing through a college prospectus and said, there's an article here about motor mechanics earning £25,000 a year. That's £4,000 more than I'm earning."
It turned out while Chris had only been working there a year, he was on a salary of £22,000, while Kay earned just £16,000, although she had 15 years more experience.
"There wasn't any problem for us discussing it," she says. "He was as shocked as I was."
As a result of that conversation, Kay, now 58, took her employer, Compass Group to court and won. She has since lost her job and is still out of work. But she says she would definitely choose to be open about pay in future if she got another job.
Sam Smethers, Fawcett Society chief executive, says not discussing pay with colleagues lets employers off the hook.
"In workplaces all over the country, pay discrimination is able to thrive and is more common than people realise because of a culture of pay secrecy which persists."
Don't ask, don't tell?
A lot of people are reluctant to ask for colleagues' salary details and even more reluctant to share their own.
"I'd probably say, mind-your-own-business, because it's not a question I would ask," says Tony Clapson who works as a junior manager for a High Street retail chain. In retail he says most people are just on the minimum wage and the pay bands for management are fairly clear. But he still wouldn't ask, or tell, colleagues about salary details: "It's like asking someone's age, isn't it?"
"It's a question which is hard to ask and hard to be asked," says Anne, 30, who works in sales for a technology company in London. She says in her native France no-one would ever ask colleagues about their pay. "I'm quite happy with it remaining a private matter."
"It's nobody's business," says Danielle Khan. "If you want to fight with your boss about what you get paid, fight with your boss, not with your colleagues." She is semi-retired, but when she ran a software company she had a policy that people shouldn't ask each other about pay, and says the result was to keep a lid on office politics.
Henry, 43, a commercial lawyer based in Singapore, says he wouldn't tell colleagues what he earns: "I sympathise over the gender equality pay gap, but I don't think that's the right way of tackling it." He thinks it's the company's responsibility to ensure there aren't discrepancies in pay. "If you want to tackle the problem, tackle it at source."
The other way the Fawcett Society aims to raise awareness of pay discrimination is by identifying a day each year as Equal Pay Day "the day in the year when women effectively start to work for free".
They suggest there is currently a 13.7% gap between what women are paid and what men are paid. Their premise is that if men and women were rewarded equally, women's pay would all have been handed out by this point in the year.
But their calculations have been questioned by the free market think tank, the Institute of Economic Affairs. The IEA says the Fawcett Society is inflating the pay gap by using the mean average to calculate their figure (taking a sum of hourly pay across the working population and dividing by the number of individuals).
The Office for National Statistics (ONS) calculates the pay gap using median earnings (comparing the rate paid to men and women who are in the middle of the pay spectrum). The ONS calculated pay gap is 8.6%.
IEA's associate director Kate Andrews said the gender pay gap as calculated by the ONS has got smaller and it was time Equal Pay Day was moved to a later date: "It was the 10th November last year, and is the 10th November this year, because it is calculated in a way that skews and inflates the data."
The IEA says using the mean average means the pay gap is distorted by the outlier salaries of a small number of high earners and doesn't reflect the experience of typical workers.
The Fawcett Society says that is the reason it uses the mean average - to reflect "that more men than women are earning higher wages at the top, and that more women earn the least".
"Each method sheds a different light on gender wage inequality," the organisation said.