My favourite work-related one is that the security question for asking the Service Desk to reset one of my passwords is "What is your favourite film?"
First of all, I reserve the right to change my mind over time!
Secondly, someone who has discussed the subject of films with my could know the answer. For that matter, if someone knew enough about me to find this web site then they could find the answer by using the search function. What am I supposed to do, never ever discuss my favourite films online again?
(I had to give them the name of my second favourite film of all time instead, then make a note to myself that when they ask for my favourite film I have to name my number 2 choice instead. Now all I have to do is never, ever change my mind about which film ranks just below 2001: A Space Odyssey.)