* It's a misspelling: Could you be thinking of a similar word? For example, "diet" or "diets"?
* It's a regional word: This word might exist in a specific dialect or language that's not widely known. If you can provide more context, such as where you heard it, I might be able to help.
* It's a made-up word: It's possible that "dyetki" is a made-up word, perhaps for a fictional character or a specific purpose.
Please provide more information so I can assist you better.