I don’t remember exactly where I first heard about this, but it came up from a number of different sources, which was itself interesting. India ‘issues’ zero rupee banknotes. Wikipedia’s article. Another article.
He gave one example where a tax official refused to process documents unless he paid her 500 rupees.
"I handed over the zero-rupee note which I always keep in my pocket," said Sundar.
"She was afraid and didn’t want to take it. She completed the job immediately and said she was sorry and asked me not to take it forward."
We sure could have used something like this in Cameroon..