Ok this is pretty simple one person gives two things they wouldnt want to do... the next person chooses which they would rather do and gives another two things.
Hope I explained that ok..
I'll give some examples...

-Whats worse? Drowning or dying of thirst?
-Whats worse? Eating one bite of pig brains or falling down three flights of stairs?
-Whats worse? Slamming your hand in a door or sitting through a three hour test?