I have a friend from The Netherlands called Mark, who's an exceptional piano-player and often when we get together on #Jamulus, we fall into these musical stories.
It's like the thing where you'd sit in a circle as kids and someone would start with 'Once upon a time, an umbrella found itself in a sausage factory with no idea how it got there.' Then the next person would come in and add to it etc.
We do this in-music with two pianos, so someone starts a line, might leave it as a cliff-hanger and the next player has to add to it, hopefully as a sensible musical follow-up.
This can go on for ages, in this case over 11 minutes. The track ebbs and flows like water, and at about the 5 minute mark it turns into a mad thing with a lot of F's in it. Just the note, not the rude words, fear not.
Anyway, this is always a very special thing for both of us, we really enjoy playing against each other, because you don't always know where the other person is going to go. Requires quick thinking and is great for ear-training.
Enjoy.