[header] How to annoy your sister [title] Steal something from her. [step] One of the best ways to bug your sister is to steal her things. [substeps] Sneak into her room and take something really important, like her ipod, her favorite pair of earrings, or the stuffed animal she sleeps with every night. 
When she confronts you about it, deny that you took it-you should practice your innocent face beforehand. You could also pretend to be really offended that she accused you.