in broad terms, a cult is a private forum.
It has one theme to it, and anyone who believes they belong within the cult and enjoys talking about the theme is welcomed to personal message the creator or any leader( in bold) and ask to be invited. As stated above, the 420 cult is about smoking marijuanna. There are hundreds of cults, so check them out interact -> cults, and see if anything appeals to you.
"They wouldn't let me play ... anymore"
"Awe I'm sorry, because your black?"