A couple of friends of mine have recently been experimenting with mentioning CALLIGRAPHY PENS a lot around their laptops with browsers open on Facebook.
They don't talk about this otherwise, in any form or medium. Sure enough, they're getting calligraphy related FB adverts now.
There's no way big ad-based companies aren't helping themselves to data from your mic. Your phone and laptop are listening devices. For most of us, this will never have serious ramifications, but still, act accordingly.