Is this question in reference to people saying that Eric Trump's analogy of Syrian refugees as a bowl of Skittles with several poisoned Skittles, then you've probably read about this in articles such as this one in The Intercept.

The background: Julius Streicher was one of the Nazis' chief propagandists, particularly regarding anti-semitism. As part of this effort, he had a series of Nazi children's books published that promoted Nazi values, including anti-semitism. One of the most widespread of these, but by no means the only one, was a book called Der Giftpilz, which features 17 anti-semitic stories. But the titular story, which is also illustrated on the cover as a bunch of mushrooms that bear the stereotypical features of Jews, is that Jews are like poisoned mushroom, and even just one poisoned mushroom can poison an entire village. These books were disseminated in schools and bookstores. There was plenty of other propaganda over the radio and in movies as well.