It is rude not to share.
It's lunch time at school and Bobby is eating lunch next to his friend Dave, who forgot to bring his lunch from home.
Bobby wants to react to Dave's dilemma.
Bobby rips half of his sandwich off and hands it to Dave, so he has at least something to eat.
Bobby tells Dave that in the future he should keep some snacks in his locker in case of situations like this.
Dave appreciates Bobby being kind and sharing with him, and is glad to have something to eat.
Dave is still hungry and jealously watches Bobby eat his lunch.