Have you ever taken a job for a test drive?

We had a guy test drive a position in my department. The test driver went through the process of getting hired as a full time employee at my company, including submitting a drug test and signing an NDA. He worked for a few days. Then he quit--presumably because he found out that we really do work very hard at my company.
Here's the odd part, we found out he never quit his old job. He just took the week off and went back like nothing happened.
If that's not weird enough, the guy who he used as a reference was on my team and he is good friends with the test driver's original manager.
I happened to mention this shenanigan in conversation at this week's Groovy Users Of Minnesota meeting. Before I got to the "We had one guy who worked for us for about two days..." when the guy I was telling interrupted by saying the test driver's name.
Turns out they work for the same company and the guy's notorious over there for the stunt.
I can't imagine how someone could muster the intestinal fortitude to pull something like that off and go back to face your colleagues.