Royal family protocol weirdness is possibly nowhere more pronounced than in their interesting food rules.

Of all the weirdness that exists when it comes to royal protocol, this one is up there—apparently, according to a former royal chef, members of the royal family don’t eat sandwiches with square corners, The Sun reports.

It all stems from a superstition that’s been passed down for several generations, the outlet writes. Former royal chef Graham Newbould—who worked at Buckingham Palace for two years and Kensington Palace for six years—said in the documentary Secrets of the Royal Kitchen that it all comes down to a fear of sabotaging the Crown.

“The royals never have square sandwiches because tradition has it that anyone presenting them with pointed-edged food is trying to overthrow the throne of England,” he said.

While working for the late Queen Elizabeth, Newbould said he never once prepared a square sandwich for her. Per the aforementioned reason, Her late Majesty preferred “jam penny” sandwiches as part of her daily afternoon tea—small, circular sandwiches filled with butter and raspberry jam.

It’s also believed, apparently, that Queen Victoria’s beloved husband Prince Albert followed the same superstitious beliefs “because he allegedly thought that eating coffin-shaped food was deemed unlucky,” The Sun reports. (Unfortunately, the avoiding square sandwiches superstition didn’t pan out; Albert died at just 42 years old in 1861.)

Other royal food weirdness was implemented down the line, like the late Queen’s banned list of foods that royals can’t eat while they’re traveling, including shellfish, since it carries a high risk of food poisoning. “It’s a very sensible move to abandon having seafood when out and about on public duties,” former royal butler Grant Harrold told Woman & Home magazine. “We don’t want a member of the royal family having a serious reaction to food poisoning, especially if she is on an overseas tour.”

Her late Majesty was also not a fan of carbohydrates, eschewing pasta and potatoes. (Well, that’s it. Not that it was up for debate, but I’ll officially never be royal.) She also hated garlic. Because he is a staunch defender of animal welfare, then-Prince Charles banned foie gras from all royal residences in 2008. (This continues into his reign as king.)

Charles—God love him—also has some super weird proclivities, like his fussiness around what he eats for breakfast. No matter where he is in the world, Charles’ so-called “breakfast box” goes with him. “He normally starts the day with some fruit for breakfast, often some plums from the garden that have been lightly poached,” former royal chef Darren McGrady told Delish. “A little juice and some muesli to go with it.”

Newbould confirmed this: “Wherever [Charles] goes in the world, the breakfast box goes with him,” he said. “He has six different types of honey, some special mueslis, his dried fruit, and anything that’s a bit special that he is a bit fussy about.”

According to The Sun, “The King is believed to follow a rigid healthy diet of homegrown vegetables, small meals, and eggs from his chickens at his country home, Highgrove House.”

The more you know!