Tinder is a popular way of organising casual "hook ups" via your phone, which means many people won't shout from the rooftops that they're using it. However, because Tinder uses Facebook for its user logins, you can find out if friends are seeking some Tinder action with a simple Graph Search query.
Type 'My friends who use Tinder' as a query in Facebook and you'll see who is (at least in theory) happy to hunt down some "special cuddles". This only works if Graph Search is enabled for your account. Graph Search is now deployed on all Facebook accounts with US English, but many Aussies use UK English as their setting instead, so it might not be available to you.
Tinder goes to some pains to maintain anonymity: you can only chat with someone else on the service if you each like each other. If nothing else, this is a reminder that nothing is ultimately very anonymous when Facebook is involved. Thanks to SecretStud for the tip!