The parent poster is correct. This is a standard practice for polygraph interviews. The pick one question, more or less at random, and double/triple/quadruple down on it until you break. Or don't.
I got "have you ever committed a crime" (and after a actually pretty cool conversation about filesharing vs recording songs off the radio with a tape recorder, I passed). A friend of mine got "have you ever had sex with animals." I don't think he enjoyed his experience quite as much.
Oh, man. I would so much rather get the animal question. For the crime question I'd just be sitting there reaching my brain about what level of teenage transgressions I'm supposed to come clean about...
Entirely appropriate as you get up and leave. Seriously. There is no other appropriate reaction unless you're terrified of retribution because it's the USSR or one of the wannabes. Price of freedom, etc. etc.
I'd be throwing in the word "Traitor" if it were me, but only on the basis that it is absolutely true.
I got "have you ever committed a crime" (and after a actually pretty cool conversation about filesharing vs recording songs off the radio with a tape recorder, I passed). A friend of mine got "have you ever had sex with animals." I don't think he enjoyed his experience quite as much.