It has been discovered that a simple string of characters sent via text message to an iPhone can have some pretty serious consequences. At best, it will lock users out of the Messages app and at worst, it can crash the entire phone or cause it to reboot without warning.
The good news is that it's virtually impossible to enter the offending string of characters by accident. This means victims of what is quickly becoming a global prank have been singled out as targets. A quick search on Twitter reveals a sea of pissed off victims.
If the person who sent you the initial buggy message sends you a follow-up message, it'll reportedly unlock the Messages app. Details about what exactly is taking place behind the scenes is sketchy at this hour although one Reddit user claims it is due to how the banner notifications process the Unicode text.
Of course, that's just one explanation as others have their own opinion, some of which are pretty silly.
Vulnerabilities like this have surfaced in the past although Apple is usually quick to issue a fix. In a e-mail to Gizmodo, an Apple spokesperson said they are aware of an iMessage issue caused by a specific series of Unicode characters and they will make a fix available in a software update.
Until then, just hope that your friends are mature enough not to pull the prank on you.