In my case, I didn't rent the car, but my girlfriend did. I signed on as the additional/primary driver and showed them my driver's license. They asked for a credit card on me, which I thought was odd, since I wasn't paying for the rental card. I, the polite sheeple, provided my credit card to them.
But when the clerk asked for my thumbprint, I asked her why she needed that, and like a good FReeper I refused to provide such private information to them.
The clerk at the desk was cool and said, "That's okay sir, we'll just remove you from the additional driver position."
I said, "Fine with me."
I didn't provide my thumbprint or my SSN mr. smartie pants.