Comedian Jack Vale can find out anything about you. No, he’s not a psychic or a stalker. He’s a social media user.

Last week he engaged in a social experiment to see just how much people share on their Twitter, Instagram and Facebook accounts. Simply by tracking recent posts in his area he was able to recognise people from their social media accounts and recount intimate and detailed information to their faces.

The shocked and slightly terrified reactions of his prank victims demonstrated that, while people may feel secure about having the profile set to public, they’re not quite so happy about the consequences.

It’s an increasing issue in an age where finding out what someone had for breakfast is simply a matter of hitting the net.

“Oversharing online is basically just human behavior translated into another form,” says Lisa Gye, senior lecturer in media and communications at Swinburne University of Technology.

“There are always those people who want to share some ghastly piece of information about themselves with you, or who sit on the train talking about their colonoscopy.” And simply being behind a computer won’t change them.

According to Ms Gye, while people are becoming more aware of their internet privacy, the real problem arises when you combine a compulsion to overshare with a lack of online common sense. Surprisingly, the real problem lies not with internet-obsessed teenagers but rather amongst older social media users, who place themselves at risk of hacking simply due to their cluelessness.

A September 2013 report by the Pew Research Centre revealed that young adults are more likely than their parents to use strategies to remain anonymous online, like clearing cookies and history, using fake usernames and deleting or editing past posts.

The biggest risk people face by not taking these precautions is “to their reputation,” says Ms Gye, “whether that be to friends, potential employers or strangers.”

Mr Vale isn’t the first to try and raise awareness about the transparency of online accounts. Websites like We Know What You’re Doing and Please Rob Me collate check-ins and status updates to confront people with their own obliviousness.

If you’re feeling uneasy about your own internet behaviour, Ms Gye has some failsafe rules for you to follow if you insist on maintaining a public profile:

1. “Ask yourself why you want to have an account – for friends and family or to generate conversation?” If it’s for friends and family, Ms Gye recommends ensuring your privacy settings reflect this by making your profile only visible to your chosen group.
2. If you’ve chosen to place yourself in the public eye either for self-promotion or to generate awareness for cause, prepare yourself for backlash. As Ms Gye says, “there are a lot of haters out there” and the usual etiquette rules do not apply online. Prepare some emotional strategies to help you cope.
3. Finally, educate yourself about the technology you are using. Read the terms and conditions of the app or website and learn how to edit, delete and post content appropriately. There is a big difference between a Facebook wall post and a Facebook message. Learn to tell them apart.

If you’re still not convinced, watch this eerie video from a Belgian communications company. It ought to sufficiently freak you out.