Meaning:
“挖” means “to dig,” and “坟” means “grave.” Literally translated as “grave digging,” this term was coined by Chinese netizens to refer to the practice of commenting on a post from a long time ago (often a post that people stopped commenting on at least two months ago) and therefore bringing it to the front of a list of discussions on online forums, such as Baidu Tieba.
Example:
A: 昨天我看到一个好久以前的贴子，讲一个香港艺人的黑历史，不知道为什么被人挖坟挖出来？
Zuótiān wǒ kàndào yīgè hǎojiǔ yǐqián de tiězi，jiǎng yīgè xiānggǎng yìrén de hēilìshǐ， bù zhīdào wèishénme bèi rén wāfén wāchūlái？
I read an online post yesterday about the dark history of a Hong Kong entertainer that was first posted a long time ago, and wonder why someone commented on it to bring it to the fore again?
B: 因为上周出来了一条关于这个艺人的新绯闻。
Yīnwèi shàngzhōu chūlái le yītiáo guānyú zhège yìrén de xīn fēiwén。
That’s because the entertainer became involved in another scandal last week.