From China Digital Space
屁民 (pì mín): rabble (literally: fart, or bum people)
The term comes from an incident involving Lin Jiaxiang, the Party Secretary of the Shenzhen Maritime Administration, who was caught on a surveillance camera harassing an eleven-year-old girl. (He had asked her where the bathroom was then cornered her after she showed him the way.) After the young girl escaped, the girl’s parents confronted Lin Jiaxing. Angrily pointing at the girl’s father, Lin shouted:
Do you people know who I am? I was sent here by the Ministry of Transportation, my level is the same as your mayor. You people are worth less than a fart to me! How dare you mess with me? Just watch how I am going to deal with you.” 我是交通部派下的，级别和你们市长一样高。你们算个屁！敢跟我斗，看我怎么收拾你们。”
The phrase, “You people are worth less than a fart to me” was picked up by netizens and morphed into the term, “fart people.”
While the term can be used as an insult, it has also been proudly adopted by netizens (see this article in Chinese entitled, “I’m a fart person; who am I afraid of!”). In addition, when discussing the relationship between the political elite and the masses, netizens often use the phrase “fart people” to designate the masses because it suggests that as far as the leadership is concerned the masses are “worth less than a fart.” Netizens have also remarked that without the ability to vote they matter less than a fart (没有选票, 我们就是个P!).