Explain your feelings of irritation to your sister. Your sister may be resorting to irritating behavior consciously or unconsciously and clearly and calmly communicating your frustration to her is the first step in bringing the subject to the forefront. Preface your feelings about her irritating behavior with the pronoun "I," which is less likely to make your sister become defensive, explains Texas A&M Agrilife Extension in their online publication "Brothers, Sisters and Aging Parents." Explain to your sister, "I feel angry when you repeatedly smack me on the back of the head. I don't find it funny." Avoid making assumptions regarding why your sister is being irritating, even when it may seem easy for you to identify her motives.

Set boundaries by stating the consequences that will result if your sister continues to engage in the irritating behavior. Once you've identified your sister's irritating behavior and how it is affecting you, you have the right to state your boundaries for what you will and will not tolerate. For example, you might tell your sister, "If you continue to press me about my decisions regarding my personal life, I will no longer be spending weekends with you." Choose a consequence that has a significant impact on your sister. The consequence should hopefully make her consider changing her behavior. Setting boundaries also ensures that you will not have to continue to be irritated indefinitely.

Elicit the support of other family members. If you have a sister who is irritating, it's likely her behavior has been endured or witnessed by other family members. Speak with your parents, other siblings, grandparents, in-laws or other siblings about the behavior of the "difficult" sibling. Ask other family members how they would deal with your sister's irritating behavior, given their familiarity with her. They can also give you perspective on whether you may need to change your behavior as well. Avoid demanding that another family member join your efforts in reducing your sister's irritating behaviors, as this can cause rifts in family relationships.

Learn to ignore your sister's irritating behavior. Marcia Reynolds, author and president of a leadership development firm, in an article for Psychology Today, suggests teaching yourself to take a deep breath and distract your thoughts at times when your sister is irritating. If she doesn't get a reaction, she may lose her desire to continue the irritating behavior. Reynolds also points out that it can help to take a long view toward irritating behavior, asking yourself whether her behavior is something that will matter next year, or even tomorrow. If not, it may be better to just let the frustration go and not engage when your sister starts up the irritating behaviors. Disengaging and letting go is not a perfect science, and you will have moments when she gets through to your core. However, the more frequently that she is unable to get a reaction from you, the more likely she will no longer resort to irritating behavior. And if her behavior is unintentionally irritating, you may find it easier to let go of the frustration over time.