Tips: Be careful of pop culture references other than the most obvious. If Player A is unfamiliar with the reference, it will be very difficult to get him/her to guess it. Depending on your audience and community, you may need to stick to appropriate gender roles - Player A is male and B, C, and D are female or vice-versa.
Gimmicks: One player persona could be one that is gradually changing ("A baby growing up to be an old man"). If any chosen personas are non-human, the character should probably be able to speak in order to answer questions.