iPhone phones home with its location? NSA's most likely listening.
Googled for something naughty? NSA's most likely listening.
Chatting on an open Internet Relay Chat server? Yup.
The key to operational security isn't that no one ever finds out; it's that no one finds out until it's too late for them to stop you. Perimeter security is a war of attrition: you will take losses and you don't get to pick them.
I have confidences I've given to friends. I don't expect them to share those secrets with others, but I'm also aware that they very well might, even accidentally. (Or the sharing got MITM'd.) Thus, instead of using shared confidences as magical shibboleths to friendship, I use them as the first step on increasing my comfort level with sharing them publicly. For instance, I was extremely ashamed of the fact that I watched porn when I was a teenager; now I can say it freely on a public forum with my name attached. There are a dozen steps of infosec stepdown that occurred as I grew up between then and now.