It's inconsiderate to pull a girl's hair.
Billy is in grade school and has a crush on a girl in his class.
Billy wants to get the girl's attention.
Billy offers the girl a dessert treat during lunch and asks if he can sit next to her.
Billy sneak up behind the girl to surprise her by giving her hair a tug because he doesn't know how to talk to girls.
The girl is touched by the gift from Billy and feels happy.
The girl who gets her hair pulled by Billy feels pain from it and is upset.