I interviewed someone once and their CV seemed like a good fit. Then he started taking about being the heir to the French throne. Instead of wasting the opportunity I asked another colleague who had a degree in psychoanalysis and we told him this guy was likely to be his co-worker. I just wanted to see his reaction about the heir to the throne of France bit which I assumed he would bring up again.

He came out afterwards confused and we asked him whether he brought it up again. He said yes.

We simply gave the guy his travel expenses which was his likely reason for attending with a trip to Cambridge paid for by us.

Bomb dropping is usually an indication of a person with a different motive. They may not be as crazy as they first seem. A free trip to Cambridge all expenses paid.