Each person adds a line to the haiku in the previous post, until it's time to start a new one.
EDIT: Sample communal Haikus from the zefrank.com fiction project:
My mouse pad is old
I have no mouse pad at all
Padless, homeless mice.
Winter wind burns eyes.
Tears like gentle freezing rain
Tongue stuck to flagpole.
Now tied up, tied down
Mistress Cruel approaches me
Now tied down, it's up