The case is among a crowd of people or area. Such indecency on the bus should not be embarrassed to ask for help loud. If found to have a walk in the desert should yell "fire" Do not shout, "Help" and then ran away as fast as possible should notice or a police officer or a journal to bring the culprits to justice. Or at least to warn the offender. That in any case the important thing is to compose it in order to choose how to survive properly.