An expiration for your phone’s vibrate setting

When I set my phone to vibrate I’d like to be able to set an expi­ra­tion time for that. Say, for two and a half hours, if I’m at the movies. After that peri­od has passed, the phone sets itself back to what it was before. Then I don’t have to remem­ber to set it back to ring, and I don’t miss a bunch of calls the next day.

For all I know, there are phones out there that do this, but I’d like to have one.