A new mishnah! When a Jew makes a gift or sale of meat to a non-Jew that includes the gid ha-nasheh, because the process of “nikor” hadn’t happened. Specifically, in the case of the whole thigh. Note that in some communities, all of the slaughterers were Jewish, and all meat was then presumed to be kosher (if sold by a non-Jew, presumably already purchased from the Jewish slaughterer). And announcements were made when non-kosher meat was on the market on a given day. But in a place without that kind of announcement, then purchasing from a non-Jew would not be permitted. Also, if the non-Jew cut the thigh that had gid ha-nasheh in it, then it might deceive Jewish buyers, which would obviously be problematic. Which leads to a discussion of false pretenses, even when nothing. Plus, other actions a person should not do because they are misleading, even if no other wrong-doing is taking place. Except possibly if it’s to demonstrate that one’s guest is worthy of honor, as per the cases of wine and oil on this daf. Plus, the horrible outcome of violating a policy of not giving food received from one’s host to the host’s children, in this case, the matter of 3 eggs. Also, in a town of all kosher slaughterers, how would the Jews make the announcement that there was non-kosher food on the given day, without it being obnoxious in the faces of the non-Jews? They made the genteel effort to refer to soldiers, for example. Note that self-deception isn’t the same problem as false pretenses.