It's mean to exclude people.
Britney likes to hang out with the girls on her basketball team, except for one girl who is very quiet.
Britney wants to have a slumber party.
Britney hands out invitations to everyone at practice, including the quiet girl.
Britney brings invitations to practice and hands them out to everyone but the quiet girl.
The quiet girl is happy she is invited and starts to feel more comfortable with the other girls.
The quiet girl is sad that she wasn't invited to the party.