A game of Over / Under is a concept everyone can get. And it being a 50/50 chance of getting the right answer makes for interesting gameplay dynamics, perfect for quick-fixes at the bus or just beating your friends for bragging rights.
The concept is that you get a random string of questions with an over/under answer and that your ability to correctly answer + reaction time sets you score, which also helps against cheating since you're probably better of just guessing than going to a wiki. It also sets up for interesting timeline questions for example religion or sports. Most things in life have a O/U value as long as you can connect your monty python'esque brain to the task.
For the full experience, meet me for a coffee, and prepare to be beat in a game of O/U