Used in casual or humorous conversation, not in formal writing or speech. That pesky squirrel keeps stealing bird food from the feeder.
Pro Tip 2/3
Mild Frustration
Expresses a light, non-threatening type of irritation or nuisance, often with a feeling of exasperation. I have to reset my password again? What a pesky task!
Pro Tip 3/3
Negative Connotation
While pesky indicates annoyance, it's not used for serious problems, but rather minor inconveniences. I'm trying to read with all these pesky notifications popping up.