Meaning:

“占” means “to occupy,” “坑” means “pit” or “hole,” and “贴” refers to “an online post.” A “pit-occupying post” refers to an online posting with just a headline and no content so that the person who leaves the post can return to edit it at a later time. Such a practice is common among some devious tutoring agencies whose staff would create a post before a significant test (such as gaokao, China’s National College Entrance Exam) and then edit it after the exam is over and the content of the test has been published. Their later addition of the test papers could be mistaken as “evidence” that they had “predicted the test” because the time of the original post indicates it preceded the test. Such gimmicks are used to lure parents to pay hefty fees for their tutoring services.

Example:

A: 听说有一家培训机构猜中了今年的数学高考题？

Tīngshuō yǒu yījiā péixùn jīgòu cāi zhòng le jīnnián de shùxué gāokǎo tí？

I’ve heard that a tutoring agency made the exact predictions about the gaokao math test.

B: 不可能，肯定是占坑贴。

Bù kěnéng，kěndìng shì zhànkēngtiē。

It’s impossible. It must have been a decoy post that used an anachronism to fool people.