The above is a parody of early twenty-first century evening news "scare segments" where a reporter describes some new trend, activity, or substance that has become popular among teenagers. These short segments often rely on slippery slope fallacies or exaggerate the extent of a new activity, because convincing adults that there is something wrong or dangerous with teenagers is an easy way to maintain viewership. The actual danger or prevalence is irrelevant. The key sign of this parody is the information being presented to the viewer/reader as though it is completely novel, strange, and dangerous, but "kids" have already gotten into it.
In this case, the perfectly and objectively innocuous consumption of stone fruits (that is to say, classes of fruit that have a large, solid, inedible seed in the center, which is the "stone") is being treated as a category of gateway drug. The above poster lists a number of stone fruits, as though they were more and more dangerous substances. But all of them are commonly consumed and have no special danger to them.
By choosing an extremely innocuous subject while parodying the language and pattern of these news segments, the above mocks the concept. People in the early twenty-first century would understand the context of the joke, and would be familiar with stone fruits.
