My sister would come in to my older brother's and my room late at night a couple of times a week.She thought both of us were asleep.My brother was but I was awake.I would act like I was sleeping but I would watch her kneel by his bed and remove the covers and put her hand on his boxer shorts.My brother is a sound sleeper and he never woke up.It was dark so I couldn't see everything but I could hear the sound of snaps being undone and could sort or see her moving her hand all around.She would stay in there about 15 or 20 minutes.She would then cover him back up and leave.After she left I would get up and go over and lift his covers and all three snaps of his boxers were undone and his Penis was laying out on top of them.