This is a variation on the traditional sentence-by-sentence story. The object is to collaboratively write a story (which may or may not make much sense in the end ? ), with each poster adding on one more sentence to the story. There's a twist here, though: each sentence must include the letters s-p-r-i-n-g, in order.
E.g.: "Soon after, she began to ponder why her intestines had turned green."
Bonus points if you can do it without using a word ending in -ing!