Enlarge Image Indranil Bhoumik, Hindustan Times via Getty Images

Many suspected Mark Zuckerberg of wanting to connect India to the internet so he could score millions of new Facebook users. But it looks like the real goldmine isn't in social media -- it's in porn.

Free Wi-Fi is offered at 23 train stations in the country, courtesy of Google and internet provider RailTel. Data collected from the station where most internet use occurs showed that the service was mostly used to find porn, reports The Economic Times.

"More than any other railway station in the country, where free Wi-Fi service was launched, the Patna railway station is on the top in the country for using internet search," said a RailTel official, "particularly [searches] for porn sites."

Hotspots at Jaipur, Bengaluru and New Delhi stations followed Patna in usage traffic, though details on what users were searching for at those locations wasn't shared.

Every day, thousands of people in India access the internet for the first time, thanks to increasingly cheap smartphones. But the phenomena of using public Wi-Fi for private entertainment is certainly not specific to India.

Wi-Fi kiosks set up at New York train stations were last month shut down following concerns that too many were loitering around the booths and -- you guessed it -- watching porn in public.

This could be just the beginning, too. Google last month announced Google Stations, a plan to help bring free Wi-Fi to buses and trains around the world. So, next time you're commuting to work, be mindful of whose phone you glance at -- you may regret it.