the.com/pet peeve

means A specific small thing that irritates you far more than it reasonably should, every single time it happens.

from "Peeve" is a late addition to English, a back-formation from the older adjective "peevish" (meaning irritable or cranky), which dates back to Middle English with a murky origin all its own. "Peeve" as its own verb/noun only emerged around the early 1900s. "Pet" here uses its sense of "favored" or "particular" — as in a pet project or pet theory — so a "pet peeve" is literally your own favored, personally cultivated irritation, singled out from all the world's other annoyances for special attention.