My experience has been that this works well for job interviews. Spot something that they seem to have struggled with and talk to them all about their solution.

My experience has been that this works well for job interviews. Spot something that they seem to have struggled with and talk to them all about their solution. Not only do you learn something but it often seems to leave an impression of you being insightful, even though all you did was ask the right question to hear about their insights. Honestly there's nothing wrong with that either. Someone who can look at your problem/solution and ask the right questions to allow you to evaluate it from a new angle is a valuable coworker to have.