since when do crackers think about garlic

It’s a reference to this:

When you are constantly anxious, no threat is too small. In January, Rick Scott, a senator from Florida, introduced legislation that would ban imports of Chinese garlic, which he suggested could be a threat to U.S. national security, citing reports that it is fertilized with human sewage. In 2017, scientists at McGill University wrote there is no evidence that this is the case. Even if it was, it’s common practice to use human waste, known as “biosolids,” as fertilizer in many countries, including the United States.