The latest leaked messages to blow up in someone’s face are some emails from Evan Spiegel, the CEO of Snapchat. These were incredibly sexist emails sent while he was in college at Stanford organizing fraternity parties.
These emails are like racist rants, homophobic tweets, and pictures of your “junk”. They are all trouble waiting to happen, and there is always a risk that they will crop up and bite you when you least expect it. If you have ever shared any potentially damaging messages, documents, photos, or whatever then you are at risk if anyone in possession of them is angry, board, or in search of attention.
Even if it only ever lives on your computer, you are vulnerable to hackers breaking in and stealing it, or to someone getting your old poorly erased second hand computer.
This falls in to the “if it exists it will leak” rant that I seem to be having to repeat a lot lately. The first rule of privacy is: think before you write (or talk, or take a picture, or do something stupid). Always assume that anything will leak, will be kept, will be recorded, will be shared. Even when you are “young and stupid” try to keep a thought for how that thing would be seen in ten years when you are in a very different position. Of course, ideally you are not sexist, racist, homophobic, or stupid in the first place.