One Saturday a friend announced: “I’m coming over tomorrow for breakfast.”

I said, “Fine. We’ll rustle up cereal . . . or eggs.”

She said: “You crazy? You know what day this is?”

“No, what? St. Swithin’s Day . . . Garbage Disposal Day . . . The Day Your Rotten Ex Remembered to Send His Alimony Check . . . what?”

“It’s Sunday.”

“So?”

“So where were you raised, Wyoming? Sunday in New York is bagels.”

“Yes, but the weather’s bad, and around my way no place to get them. I mean, Bergdorf’s doesn’t even do bialys.”

Came the second call. On a rainy street. The designer bagel call. Asked my Methodist friend: “Plain or rye or with poppy seeds?”

“Plain.”

“Because the inside could be white or brown.”

“Look, this is no mother-of-the-bride gown. We’re not debating colors. I want plain. White.”

“Toasted? Not toasted.”

“Not toasted.”

Call No. 3. From deep inside a deli. You could smell the sturgeon through T-Mobile. “I’m at the counter. Should I get chopped egg salad, tuna, lox or do you want with a schmear?”

“Just cream cheese.”

“Right. With or without scallions?”

“Bring the lousy bagel. You don’t have to be Mensa.”

This round, big-calorie bread with a center hole is as Sunday as Mass. My driver of 35 years is Guyanese. My housekeeper of 15 years is Indian. To them, a bagel beats sex. When I’ve done something especially kind and nice — which is rare — my Sephardic assistant treats us to a bag of bagels. That this delicacy was invented by a dentist who needed money is untrue. Fact: In 1600, in European shtetls, a childbearing woman clutched a ringshoe symbol of life. Also, for saving Austria from Turkish invaders, a Viennese baked this stirrup-shaped tribute for Poland’s horse-loving King Jan Sobieski III. The bagel arrived here in Eastern Europe’s 1800s immigration. Threaded onto dowels vendors hawked them on the street.

In 1907 came the International Bagel Bakers Union. Back before King Jan Sobieski III of Poland, teenage model me was crowned “Miss Bagel” by the Brooklyn Better Bakers Union. My tiara? Shellacked interwoven bagels. Let none say I don’t come from quality. As a specialist in this chewy, doughy, centuries-old tradition, I’ve seen them sold everywhere. China, Australia, France, Turkey. The Congo, no. Also in assorted American cities. With great respect, I hereby announce those are junky. Thin, stiff, flat. Who knows why since fortune cookies, possibly manufactured by Pennsylvania Amish, seem just as tasty and stale as those stamped “Made in Japan.” They say something’s special about New York water. I only know a Midwest bagel is as appetizing as a teething ring. Supermarkets also sell them frozen. Oy. Taste like linen.

I mean, this New York staple is not exactly fashioned by Oscar de la Renta. It’s yeasted white dough, boiled. Astronaut Gregory Chamitoff’s 2008 Shuttle to the International Space Station took a batch of 18 sesame-seed numbers. If they came with or without a schmear, this I don’t know. Or, if you’re in some interfaith marriage, you could slather it with Smucker’s or Skippy.

The how-to devourment ritual: There are toast versus do-not-toast gourmets. Some gnaw the entire thing, whole, handheld, which is scarcely Emily Post’s preferred bagelnosherization. Others hack it in half. Should you be dainty (a no-no for bagel eaters), each half may be sawed into quarters. Pinky akimbo, one then elegantly crams eighths into one’s mouth even at Buckingham. Although, except maybe now because of Princess Kate’s Jewish background, Her Majesty’s equerries rarely stick lox and a schmear at the Queen’s table.

There’s also the dieter who pulls the bread out from the inside. Then what’s the point of the bagel? That’s like scraping salt off french fries. Stripping a pizza of its cheese. Sniff bagel purists: “A bagel-less bagel? Might as well chew a pumpernickel heel.”

Understand, said tasties are Day-Of. Purchasing these carbo-loaded wheels Thursday for Sunday is a no-no. We do not stock, freeze or recondition them with a splash of water in a microwave. We do not stuff turkeys with the leftovers. These are not month-old crappy cardboard muffins whose blueberries now sport beards. Somewhere in the Dead Sea Scrolls it’s probably inscribed that we are talking Day-Of.

Sunday in New York is bagels. No difference what the weather is. Could be so hot the Kardashians are lifting their skirts for other reasons. It’s a bagel and iced coffee. Could be so cold that you’re told your stockings are wrinkled and you’re not wearing any. It’s a bagel and cappuccino.

Although a bagel midweek is frowned upon, at the very instant I’m writing this, I am pleating one — with lettuce, tomato and mayo — into my mouth.