Years ago when I interviewed at Google, upon walking into reception, I was required to sign an NDA which stated that I wouldn't tell anyone about my interview, and that I had not told anyone I was interviewing.

I was kind of stranded in Mountain View unless they schlepped me back to the airport because I happened to be flat broke when they flew me out, so I just signed it, but I consider it laughably the craziest, most paranoid, least binding NDA I have ever signed.

Talk about Duress. ;)