There's a huge difference between wearing a t-shirt, which makes the information available only to people who see you wearing that t-shirt, and becoming a fan of a brand on Facebook, which makes the information available to who knows what Facebook affiliate.

In one scenario, you have full control over when you signal that information and when you stop. In the other, once you send out the signal... congratulations, you're now in several databases and have opened yourself to all sorts of soliciting.

You can easily stop wearing a shirt when you change your mind about the topic.

Once it has been on the internet, it is forever.

Not saying you're wrong, but I don't think it is exactly the same.

Maybe tattoos?

> Once it has been on the internet, it is forever.

If that were truly the case, we wouldn't be so worried about NSA retention of data.

My phone conversations aren't supposed to be "on the internet."

This is probably something worth saying louder.

If you commonly display $information in all sorts of settings, then $information is not ipso facto private and leaking that information further is not a privacy threat.

(Of course, it can be used as an input to deanonymize you in some data-mining system, so there's that...).