So sometimes when you go to a restaurant, you have the option to customize your order. You might say “I want a hamburger with no cheese, but a little bit of ketchup and mustard.”
Well, in ancient Greece, there was a group of people called the Spartans who were very serious about their food. They wanted simple, healthy meals with no fancy extras. They would only eat a special type of meat called “laconia” which came from the region of Laconia where they lived.
When other Greeks wanted to make fun of the Spartans for being too serious, they would say “Oh, do you want an order of ‘laconia’ with that?” as a way of mocking their Spartan diet.
So the “laconia order” is really just a way of making fun of someone for having very specific, simple tastes. It’s like saying “Oh, do you want plain chicken and broccoli or are you feeling adventurous with your taste buds today?”