Missing option: no, because I hate it. That's essentially my answer. I have accounts with both Facebook and Twitter. I understand how the authentication works,

Missing option: no, because I hate it. That's essentially my answer. I have accounts with both Facebook and Twitter. I understand how the authentication works, and I'm not afraid such requests are scams (note: that's mostly a subset of not understanding how it works). I don't want my online identity tied to a third party account whose operator has few obligations to me.