An anonymous computer programmer hacked Tinder and caused straight guys to unknowingly flirt with each other.

The California-based hacker changed Tinder’s API, creating a catfish programme that fools men into thinking they’re talking to women — when in fact they’re talking to each other.

The results are amazing.

The hacker, dubbed ‘Patrick’, created a dummy profile with pictures of attractive women (used with their consent) that causes the men to talk to each other. Through the fake profile, the men are fooled into believing they are speaking to the woman whose picture is used, but they are speaking to another man who is chatting to the same profile.

Patrick met his current girlfriend on Tinder but has also seen the nasty side of the app, with his female friends complaining about abusive or disgusting comments from male users of the app.

“The original idea was to throw that back into the face of the people doing it to see how they would react,” he told The Verge. “Tinder makes it surprisingly easy to bot their system. As long as you have a Facebook authentication token, you can behave as a robot as if you were a person.”

Patrick estimates he was overseeing 40 conversations within the first 12 hours. He scrambled phone numbers and stepped in when a real-world meeting was imminent, but he doesn’t feel bad about his prank: “They ignore all the signs, they ignore all the weird things,” he says of the men. “When someone is so quick to meet up without any detail or know anything about the person at all — maybe it’s deserved.”