I had one recently where I was locked out of my medidata/Rave account for not knowing the answer for "Who was your best friend in 4th grade?" I seem to recall that I had a
lot of different friends in 4th grade, and it was also blurring with crossover to 3rd and 5th grade etc.
After spending hours on hold and escalating through the support, they finally unencrypted my answer and told me what it was and I had put our cat! Totally did not remember that. Since then I've started paying attention to the questions I select when I set up the passwords and trying to idiot-proof myself to something I will actually remember in 7 years, not trying to be clever in the response.
As a bonus stick you in the ribs "revenge," when I finally was able to get it reset up and log in, I was gobsmacked to see that the customer support reps had assigned me mandatory extra remedial rave training to be completed before I could access the functional areas of the software! Lol. Touche.