"His Tinder bio says WHAT?" Rafi Letzter/Tech Insider Tinder is experimenting with a new feature that lets you organise group dates — but people have reacted with alarm after realising it also shows you a list of all of your Facebook friends that use the dating app, and lets you view friends' Tinder profiles.

Tinder Social, which is only being tested in Australia for now, is intended to let you organise group events with friends and other groups of new people. "Whether you’re looking for groups you share common interests with, or you’re looking for a completely new adventure, Tinder Social is a better way to go out with friends," a blog post announcing the feature explains.

But the feature is automatically activated for users in the test group, rather than being opt-in, multiple Tinder users who have the trial told Business Insider. This means you're added to public lists that all of your Facebook friends with Tinder can see when making groups — even if you didn't want to broadcast the fact that you use the app.

Facebook friends (of either gender) on Tinder can also add you to groups without your permission, and from there view your full Tinder profile.

Here's how it works: You click the "Start a group" button to create a group, and it takes you to a list of your Facebook friends who have the app. From there, you can go on to match with other groups and have group chats over the app.

You can also view which of your friends are already in a group.

The setting which lets you opt out of Tinder Social. Chloe Mac There is an option in the Settings menu to prevent you from being added to Groups, hiding you from the lists — but the feature is opt-out rather than opt-in, and alarming some Tinder users.

"When I first saw that I could see everybody I was a little bit shocked because I figured that a big app like this would give a little more privacy than that, especially considering when first signing up they make a big deal about no one on facebook being able to see that you are using this app," Australian Chloe Mac told Business Insider.

"I think many people might find it somewhat embarrassing and I think that there should have been a warning or an option to turn it on rather than just having your name out there for all your friends to see."

Other people are reacting with a mixture of worry, surprise, and mirth to Tinder Social's lists.

Tinder VP of communications and branding Rosette Pambakian told Business Insider: "Any users who would prefer not to be added to groups can opt out of Tinder Social through their settings. We are only testing it at this point, but it's important to note Tinder's not a secret considering 70% of users download Tinder because their friends recommend it. "

There's also broader confusion as to the purpose of Tinder Social. Tinder is a dating app, so the natural assumption is group dates — but the announcement blog post seems more aimed at platonic get-togethers. "What takes an average night out with your friends to the next level? Meeting great groups of new people, and turning a basic night out into a night you’ll never forget," it says.

But Tinder also has a reputation as a hook-up app — and some are suggesting that Tinder Social has some very X-rated applications.

Tinder oftens tests features in Australia before rolling them out worldwide. The "Super Like" — which lets someone indicate you're really keen on them — was first trialled in the country before being introduced for all users.