This is the old drinking game you may have played at parties. You can drink if you want, but it's not required for online play ;)
The person above you will say something he/she has never done. You will answer with a simple "I have" or "I haven't either."
(in the normal game, you would take a drink if you have done what the first person has not.)
Then, you post your own 'Never have I ever' and wait to see if the next person has or hasn't.
Example--
Person 1: "Never have I ever been to New York"
Person 2: "I have. Never have I ever eaten lobster"
Person 3: "I haven't eaten lobster either. Never have I ever shaved my legs."
I'll go first with
Never have I ever read a Twilight book
