In addition, the content that China viewers watch is much more diverse in terms of country of origin, from the U.S. to China, South Korea and Japan, Wang says.

FORBES: Tudou CEO Gary Wang On Online Video, Mobile and Producing Original Content

China thus leads India and South Korea as the primary country of origin for foreign students.

ECONOMIST: Chinese college students

The origin of the practice is unclear - padlocks have appeared in China for years at sacred sites, and there was a flurry of padlocking in the Hungarian town of Pecs in the 1980s, when university students locked them on a bridge next to the university either as a symbol of undying love or their determination to finish their courses.

BBC: Locks say I love you

Google hasn't played up its origin, even though the vast majority of electronics are manufactured in China or other countries where labor is cheaper than in the U.S. A Google spokeswoman did not immediately reply to a message seeking comment for this story.

CNN: Google's new Nexus Q: Made in the U.S.A.