She says that she always liked to tickling-torture her brother. She puts on top of him and tickes him until he almost pees on his pants. One day during her "torture" she noticed his cock got hard and she like to feel it rubbing her pussy, so she tought trying to do it in the morning because both only had pijamas and she could feel his cock better, then it didn't took much for her to start touching it very descritly, with her hands. Now he already knows that when she enters his bedroom in her robe and panties he has to put it all in.