Rational: hence my point. If YO wants to pluralize as tallisos because that is the vernacular in spoken Hebrew, gezunterheit. But then he should not be outraged at those who pluralize talleisim because that is the vernacular in Yiddish.
YO: one reason we call it Shalosh Seudos is because there is a mitzvah to eat three meals on Shabbos. When eating the first two, however, there is no indication that we are doing it for the mitzvah, since it is normal to eat a meal at night and a meal in the morning. When we eat the third meal, however, which is usually much earlier than the evening meal is typically eaten (especially in the winter months),we are showing that even those first two meals were eaten not because of convention, but for the mitzvah. Therefore we refer to that third meal as Three Meals, because that is the “megaleh” on all three.