Meaning:

“郫县,” the ancient name of Pidu District in Sichuan’s capital city of Chengdu, is best known for the spicy fermented soy paste produced there. The fermented soy paste, or “豆瓣酱” (dòubàn jiàng) in Chinese, is said to be the secret of many delicious Sichuan-style dishes. As this Pidu District specialty is the namesake of Douban, an interest-based social network featuring user-generated contents, Chinese netizens joshingly call Douban users “郫县网友.” (“网友” literally means “netizens.”)

Example:

A: 你昨天转给我的那篇影评是哪里看到的？写得真不错！

Nǐ zuótiān zhuǎn gěi wǒ de nàpiān yǐngpíng shì nǎlǐ kàndào de？ Xiě de zhēn búcuò！

That movie review you forwarded to me yesterday is very well-written! Where did you find it?

B: 来自郫县网友的贡献。

Láizì píxiàn wǎngyǒu de gòngxiàn。

It’s contributed by a Douban user.