Cherrystein (Full title: Cherrystein I - Berry Potter the Philosopher Got Stoned) was a mod that was announced on July 21, 2003. The authorship of the mod was not mentioned. A title screen and an enemy was posted.
An enemy waiting to get popped
The mod was mentioned in connection with Pineapplestein and Monkeystein, though it is not known whether the authors of those mods had anything to do with the project.