I remember a few "knock your neighbor" games that I used to see in here and steal for other boards.
The Fantastic Vending Machine!
You post a few objects that would be entered into the vending machine, the following poster would made something outlandish with it and post their own items to be responded to.
Wish Corruption!
The poster wishes something. The following person grants their wish, but at a price - Terrible, yet silly. Then they make their own wish to be corrupted.
An Exquisite CorpseI like to think I could play this game better now than when I was first introduced to it, but I haven't had the opportunity to try. Also, gathering all the peices takes for-ev-er.