I just thought I'd pass this on. My daughter just came home and her iPhone 5c was turning on and rebooting. There is a text message that will shut down your phone and lock it in a loop of shutting of and on. They just discovered this a couple days ago and kids are sending the text to their friends thinking it's funny. 

If you you receive the text, you're done and your phone will shut down. Apple is working to fix this asap. I was lucky enough to delete the message with the text and it seemed to fix the problem. I read that if you turn off 'notifications' it may prevent this from happening to your iPhone. 

Its all all over the news as of a few hours ago. Here's a link that may help. 

http://9to5mac.com/2015/05/27/how-to-fix-ios-text-message-bug-crash-reboot/