Yu Gang, a 32-year-old migrant farmer worker in southwest China's Chongqing Municipality, has been in a good mood these days, for the mayor of Chongqing had called for citizens not to discriminate against migrants but show them respect.

Yu has been working as a porter, called "Bang Bang" in the local dialect, for over a decade in the mountain city of Chongqing. "Bang Bang," a somewhat discriminatory term, actually refers to the pole that a porter uses to carry things for local people.

The "Army of Bang Bang",  which comes from rural areas, can be seen almost everywhere in Chongqing. When a local resident cannot carry his or her heavy belongings in street, he or she just needs to cry for "Bang Bang," then a "Bang Bang" will come on for business.

As a "Bang Bang," Yu said he does not care about how tiring, hard and dirty the job is. He is most afraid of "being looked down upon".

Each year, more than six million farmers leave countrysides for cities for jobs in transportation, construction or cleaning. Chongqing itself absorbs 400,000 new migrant farmer workers annually.