The first time was a very uncomfortable five days where they tried to convince me to say where I was going. I was heading to a competitor and they figured that much. I finally had a heart to heart with my manager and explained that if they trusted my integrity then they would know that I was not going to take any "trade secrets" with me. They backed off at that point and the rest of my stay was more pleasant.

The second time was at the next job. They asked me to stay and I said no. Then they said, "what if your offer were to disappear?", implying that they were going to somehow going to make enough trouble to have my offer withdrawn. I made it very clear I wouldn't respond to their threats and they denied making threats and didn't make them again.