Yeah, something like that is super easy. I actually wrote an article about the so-called brain wallet: https://steemit.com/bitcoin/@flauwy/how-to-create-a-secure-brain-wallet-store-your-bitcoins-in-your-memory
Feel free to write your own one. I am happy when we have more articles about memory techniques. I am building a community here pulling in memory athletes from all over the world.