I was asked this numerous times I college and it gave me anxiety every time I had to answer it. I simply could not understand why anyone would be interested in my response, so I couldn't synthesize anything to my audience (the person asking).
It sounds like the trouble is that people are putting a lot of effort into trying to come up with a detailed lie that will flatter the professor's expectations, when (as I read the OP) the professor has no expectations and actually wants the simple truth. So everybody loses.
Maybe teachers need to start putting a "there are no wrong answers" disclaimer on these things.
