Ran into these guys at an event a few days ago, then again on Marine Drive two days later. Their "Batti Bandh", they told me, is not fully understood. The second word is not the Hindi word for "close" or "off"; it is the Hindi word for "strike", as in the "bandhs" we know well. (For you who know Hindi, note the way the word is spelled). I promised to point that out when I wrote a note about them.
But whichever it is, it's a good thought. Turn off your lights and appliances for an hour this evening.
See you in the darkness, 730pm. Be there or be bare.