Start by thinking of a tangible object; animal, vegetable, mineral, etc... but not a specific person, place or thing.
Go here and play Twenty Questions
I tried twice, first with Pipe Organ and next with Goat and it got both of them before we hit the 20th question. This is downright eerie... From their website:
20Q.net is an experiment in artificial intelligence. The program is very simple but its behavior is complex. Everything that it knows and all questions that it asks were entered by people playing this game. 20Q.net is a learning system; the more it is played, the smarter it gets.
