There's a whole science dedicated to the universality of human expressions. Across vast continents and endless oceans, humans make the same face whether in a state of grief, joy, or disgust. More or less.
The face of the Indian street vendor clearly said "Oh, FFS!"
I had made the universal tourist mistake of paying for a cheap product with a ridiculously large bill. The bottle of mango juice I needed so desperately to cool down in the mad-dog sun came to 20 rupees. The smallest denomination I had was 500.
This created somewhat of an impasse.
Eventually, with much universal gesticulating on both sides, I received my change. It seemed broadly accurate, and I now had some more sociably acceptable currency, so I didn't feel hard done by.
I've always had a funny relationship with money. I baulk at paying £5 for popcorn at the cinema, but think nothing of buying a £200 hard drive. Just the way I'm wired, I guess.
But spending money in a foreign land is very confusing. I mentally convert everything back to pounds sterling, and compare the price with what I'd pay at home. Common enough, I suppose. Then I try to mentally match it to the local economy.
"Yes, that's cheaper than what I'd pay at home - but it seems ridiculously expensive compared to that thing over there."
A group of us went out for a meal in an up-scale restaurant. The food was exquisite and the service was impeccable. Total cost? Maybe £30 per person plus tip. Not bad. Not bad at all. Cheaper than a similar meal in London. I tried hard not to think about the hoards of people outside the guarded perimeter who were on a dollar a day.
The next night a bunch of us went to dinner with our Indian hosts. There were eight of us. The beer flowed liberally, the food was piled high, the chocolate cake was en flambé.
Total cost was around £10 per person. This was a big deal. "Still," remarked one of our hosts, "it's good for team morale."
"And it's only once a year," opined another.
On the journey back, the taxi charged us 700 rupees for a 200 rupee journey. There's a lesson in there somewhere.