Basically, Someone suggests something completely random and you have to say something that relates to it somehow, and the next person has to say something which relates to the last suggested idea and so on. I'll give an example.
Poster 1: Cheese
Poster 2: Milk (Cheese originates from milk)
Poster 3: Cookies (Cookies and warm milk!)
Poster 4: Chocolate (In cookies)
It's a really simple game, and you don't have to explain where the word comes from, but you might want to if it's not all that obvious.
And maybe try not to say the same word twice in close succession.
Its also a never ending thread so no need to pick a new word
)
Okay! I've explained it!! I'll pick a word!!
Chocolate