Because in Farsi the word for piss is lanat (a very bad word) and they are probably referring to the fact that Muslim Persians say lanat be Yehodi meaning piss be on the Jews. Im glad most of my family got the hell out of Iran and went home to Israel. Lanat to all Islamic Persians!, although the secular Persians hate Jews too. We can thank The damn Persians for Purim, which is coming.
But we also learn that Cyrus the Great, the Persian King, allowed the Jews in exile in Babylon to return to Eretz Yisroel to build the Temple...
The sages of the Talmud have an interesting view of Cyrus..
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http://www.webshas.org/torah/bichtav/tanach/purim.htmUnder the Rule of Persia before the Purim Story
The path of prophecies which were conveyed from Chanani to Nechemyah to King Artachshasta/Cyrus/Darius: Rosh HaShanah 3b
Whether King Cyrus was benevolent or not: Rosh HaShanah 3b-4a
True identity of King Cyrus, King Darius, and King Artachshasta: Rosh HaShanah 3b
How far Darius's reign extended: Megillah 11b-12a
The power of Darius's blessing to Daniel: Megillah 15a
The 23 years of Evil Merodach's reign: Megillah 11b
Evil Merodach's release of Yehoyachin: Megillah 11b
When Cyrus declared that the Temple could be rebuilt: Megillah 12a
Gd wanted Cyrus to build the Temple himself, and Gd complained to the Mashiach when Cyrus left it up to the Jews, instead: Megillah 12a
Cyrus' motivations in his donations to the Temple funds: Rosh HaShanah 4a
Cyrus' motivations in building the Temple Walls with certain vulnerabilities: Rosh HaShanah 4a
Cyrus' wives: Rosh HaShanah 4a
The Persians' similarity to bears in physique and habit: Megillah 11a
How far Cyrus's reign extended: Megillah 11b
http://www.rabbiwein.com/Cyrus-the-Great-brGreat-NonJews-in-Jewish-History-P667.html