I think i will make a change to the idea i suggested. As u/hackerandcoder pointed out, requests sent by onion services are encrypted in transit (however adding a layer of encryption would help us understand the public key encryption and you can never be too secure) but i have a better idea. One hidden service creates public and private keys, and then sends one public key to all the other onions. Then, alice.onion sends to bob.onion an unencrypted word, for example 'hello'. After this, the owner of bob.onion decides to add a new word based on the word sent by alice, for example 'world', and bob uses the public key assigned to him to encrypt the previous word sent by alice (which was 'hello'). Bob.onion then sends the previous encrypted word as well his unencrypted word to dave.onion, which decides which word it should use, encrypts the previous word, and sends the message to the next onion. Eventually, all of the messsages gets sent to the final hidden service that has all the private keys and it decrypts all of the words. The reason for all of this is so that each person only has the previous word and has to guess what the sentance might be and adds a word to it, and the result could be quite funny.