To be honest, angel21, I doubt very much that your colleague realises what they are doing and how much it is irritating you. If they do, then it sounds to me as though it is some sort of lack of self confidence issue in them. If I were you, I would just carry on regardless, doing the best job you can. If you have any sort of staff report, annual review etc, then that might be your chance to raise the topic, diplomatically, along the lines of, I sometimes feel you don't have much confidence in my ability to carry out certain tasks. I worked in an office for over 40 years and believe me there are a thousand worse, more revolting and stressful habits your work colleagues can display!! Good luck.