Cell phones, for all their utility, are more often an annoyance than a benefit. Many businesses, movie theatres for example, post signs exhorting patrons to turn off their cell phones so they don't disturb others.
Teachers are faced with distractions in practically every class. This ranges from students simply not paying attention because they're too busy texting to cell phones ringing while teachers are attempting to do their jobs. This isn't just in university either.
The advent of cheaper cell phone plans means kids in high school and junior high are also disturbing their classrooms with their cell phones.
Churches have this problem too, and cell phones interrupting prayers and sermons is an annoyance to both worshippers and pastors alike.
Westminster Presbyterian Church has gone so far as to levy fines against parishioners if their cell phones interrupt church service, and one talented filmmaker in particular has made a video explaining this system to those who come to church to worship on Sundays.
You don't have to be a church-goer to appreciate this spectacular example of making a point with humor.