When my brother and I were kids we used to play a storytelling game. The game involved a series of imagined stories acted out by real characters. In fact, the characters were ourselves.
Taking turns, each of us would create a scenario and place the other in that scenario.
I'd make up a scenario where my brother was walking down the street with a basket full of eggs and make him trip and fall in the story, breaking all the eggs break all over himself in front of a girl he had a crush on. In my story, she turns and starts laughing at him.
What does he do next?
At any point the person who is telling the story (in this case it would be my turn) can say, 'truth or dare, stories' and (in this case) my brother would either have to tell the truth about how he'd get out of that situation, or take a story dare which means the I would dare him to do something crazy in the story, making the situation worse and more awkward and embarrassing, (such as run down the street smearing the raw eggs on the girl he thinks is cute , etc. ). Usually it something really embarrassing that will be part of the story-line/plot from then on (that means at any point in the story it can be referenced). But the dare can be something funny, nice ... anything. It just gives you a power-play on where to take the plot. Everything that happens in the story except a dare is negotiable with the storyteller.
The more players, the more interesting the stories get. Your combined imaginations will take you on a strange adventure. You're only limited by your imagination.
Have fun with it! As Oscar Wilde put it, "consistancy is the last refuge of the unimaginative."