I'll go and check it out Yayi.
I don't think that there are 'rules' though per se, they are just for fun.
Ok, just went and read them. One of them says that you pick 5 letters, and than the person has to make a sentence using those letters. The other one seems to use 8 letters and you choose those eight letters by the previous persons answer. If you need more clarification, either read the first post of each thread where it states the rules. Or perhaps PM the person who started the thread for more explicit instructions. Thanks!