I just read this question: If you were asked to sing or do other weird things at a job interview, does this mean that the employer is not taking you seriously?
The common consensus seems to be that a request like that is for testing the candidates reaction (to stress or surprise). Let's say that's true. How are you supposed to react and what kind of reaction leaves what kind of impression?
Do you appear like someone that can be pushed around if you accept?
Do you appear to be boring and stiff if you don't accept?
Let's assume you'd do anything to get this job.