Any iPhone user knows how helpful Siri can be. The virtual assistant can check email, send texts, get sports scores, tell you the weather, give you a wake-up call, sing you a song, even put you to sleep with a bedtime story. However, if you say one thing in particular to Siri, your device will crash.
By going to your phone's voice input and saying "hyphen" repeatedly, the device will crash. Some people have been tricking others into doing it too, suggesting they activate Siri, say "hyphen" five times and see what happens. Fortunately, while the phone does temporarily crash, it goes back to the home screen and no real damage is done.
Also, Apple became aware of the issue and has since fixed the bug in one of its many updates, so if you've been keeping your iOS current, it won't be a problem. However, if you use a phone with iOS 12.1, you could be susceptible to the issue.
That alone should make you want to update your system, but if not, there is also a far more serious security vulnerability with un-updated devices. Apple recently warned customers about an issue that allows hackers to get full admin access to phones, which means they can take complete control of it. So be sure to update your phone.