unless of course you had a second phoneSlightly off topic from the OP, but I was at a quiz recently where you had to use your mobile. Downloaded an app, logged into the quizmaster's dedicated wifi, then answered his questions using your mobile. You couldn't get out of the app to get the answer on your own phone, as it would log you off his system, and you only had ten seconds to answer and it closed the question after that, so you couldn't go back to it. Also far too quick to check the answer on someone else's phone, so pretty much eliminated cheating.