The boy may run back to his group so when the girl turns around, he may point and laugh at one of his other friends, turning the blame on him.
Very damaging to the girl's self esteem unless they can take a joke.
Chubby Girl's Friend: "What?? Who was it??"
Chubby Girl: "I don't know! He ran back into that group of guys who were just laughing!! *points and cries more*"