Stands for 'What would you do if...'.
An ideal game for long car journeys when I Spy or The Alphabet Game have just lost their touch. Alternatively a good way to approach awkward questions. Or silences.
Car Journey: "WWYDI a giant space monkey appeared on the roof of the car and tried to eat your brains?"
Awkward questions: "WWYDI I told you that I had secretly been sleeping with your brother?"