One person will post a food - any food. Then, the next person will respond "yum" if they like that food and "yuck" if they dislike that food. In turn, they will post another food item for the next person to respond to.
Here's an example:
Post #1:
Sushi
Post #2:
Yum!
Taco
Post #3:
Yuck!
Pizza
Post #1:
Sushi
Post #2:
Yum!
Taco
Post #3:
Yuck!
Pizza
