A friend recently returned, seemingly traumatised, from what he described as "a terrible date". After much prompting, he relayed the reason in a hushed and horrified voice: "She tried to force me to steal money from a car park machine."

I was fascinated. Had the date, mistakenly thinking she had spotted criminal potential in my friend, decided to enlist him – under the cunning guise of sharing a romantic evening – as her accomplice in this most unglamorous act of theft? Had she brought a screwdriver along, or a whole toolkit? And if she had pulled off this relatively small-scale job, did she envisage the pair of them graduating to train station ticket machines, drinks machines in sports centres, or perhaps even bank jobs? It was hugely intriguing.

The truth, sadly, was rather less so. My friend had parked, gone to pay for a ticket – and the machine had given him an extra three pounds in change. "My date insisted that I should steal this money and keep it for myself!"

It was hardly Bonnie and Clyde. "That's not stealing," I lamented. "Anyone would have picked up that cash."

"But it wasn't my money," my friend protested.

"It would have been if you'd taken it!" I pointed out.

He stared at me, confused. "But that would have been dishonest!" he said.

I felt faintly abashed. Was my friend, as I suspected, being painfully moral? Or was I myself sliding down a slippery slope to a life of crime and soap-passing? Was it really just a short park-and-ride from appropriating errant change to stabbing dogs in the street?

I tried another tack. The friend did realise, I hoped, that when he hadn't collected the spare three pounds, the person behind him in the parking meter queue would have scooped it up?

He agreed that this was quite probably the case, but that was their problem.

"Problem?" I echoed, incredulous. The three quid wasn't their problem – it was their ice cold pint, their big juicy cheeseburger, the hot comforting bag of chips that they wouldn't have otherwise been able to buy.

Convinced I was right, I called a friend who happened to have studied criminal law, and recounted the story, certain that he would laugh and deem friend No 1's views ridiculous. Instead he replied earnestly: "He's right – it is stealing. Admittedly, you'd be unlikely to be prosecuted for it, but there have been cases of people taking extra money from broken cash machines and being found guilty of theft." Friend No 2 claimed that he wouldn't have taken the meter money either.

I was perplexed. Surely it was a victimless crime – 300 pence, which would only ever have been earmarked for some dull council activity, expelled by a machine that wouldn't exactly be devastated at its loss? It wasn't as though some old lady had dropped her pension money in the street. The aesthetically displeasing machine would continue its whirring and collecting, oblivious to its moral-conundrum-creating error.

I called friend No 1 and told him he had an ally. He said he wasn't surprised. I then warned him that his skyscraping ethical expectations would prevent him from ever finding a girlfriend. If he went on to sever ties with every date who failed to adhere to his unrealistic moral code, he could consign himself to a life of eternal disappointment. He told me that this was irrelevant, and pretty much what he was expecting to happen with women anyway.

After this, despite my stance that day, I kept thinking about the times that I had picked up stray cash, taken a one-stop train journey without getting a ticket, or rejoiced at a pricing oversight on my Sainsbury's receipt – and I started feeling vaguely embarrassed. I wondered how both friends would feel if they knew about those minor amoral moments, and whether they would still want to be friends with me. Even though I felt that they had overreacted on the parking meter issue, I resolved to be more honest in the future and live up to their expectations, even if no one else did.

However, as I've yet to be challenged on this resolution, I suggest that the Guardian test my virtue by overpaying me vastly for this article – then wait to see if I return the cash.