I thought this could be a pretty fun and interesting game. Basically, you say a statement starting with "Never have I ever..." and then finish it off with anything you want e.g. "Never have I ever... gone to sleep without brushing my teeth." the person below will then either say "Never" or "I have" and then come up with a new statement for the next person to answer.
I'll start:
Never have I ever... smoked.