Because it vibrates during the best times to run and pee. That way you never have to look at your bright phone in a dark theater. At the Alamo Drafthouse in Tex

Because it vibrates during the best times to run and pee. That way you never have to look at your bright phone in a dark theater. At the Alamo Drafthouse in Texas looking at your phone even once can get you removed from the theater if you're noticed.