I have to hand it to S. D.; she's found a great way to torture S. F. that makes it almost impossible to get angry. She has begun to open S. F.'s room door, yell, "I really love you!" and then shut the door and run away. I think this is a great, creative way to drive your older sibling absolutely crazy while making it hard for them to complain. It's 4 year old brilliance at its best! I only wish I'd thought of this method when I was little. I could have really driven my older brother nuts.
Yes, we are disciplining S. D. for bugging her older sister, even though it is to say, "I love you," but I've got to hand it to her for creativity in older sibling torture methods.