An oldie but a goodie. I'll think of something specific and you need to ask me questions to discover what it is. I can only answer yes, no or irrelevant. For those who don't know it, the idea is to start out with fairly broad questions and work your way down to specific ones. The idea is to guess within 20 questions, but we'll keep going until soemone guesses correctly (then they think of a new one). Guesses as to what the object is also count as a question used up.