There's nothing worse during a movie or performance than hearing someone's phone go off. Most people solve this problem by turning their iPhone's ringer off not realizing how loud a vibrating phone can sound in a quiet theatre.
Next time you're out, instead of simply turning your ringer off put your phone on night instead. Activating the moon-like symbol will fully silence your phone while still allowing messages and notifications to be delivered.
Be kind to your fellow movie or theatre goers and put your phone on night.