You can generate BIP39 wallet seeds at https://iancoleman.github.io/bip39/.
This tool uses a Markov model of a text corpus to generate sentences which encode Bitcoin wallets by including BIP39 words in the text.
You should only use the tool directly on the web to play around (not least because I still don't have any HTTPS...). If you want to use it for real purposes you should download the code off Github: https://github.com/jes/stegoseed and run it on a computer which doesn't have any Internet access, to make sure nothing can exfiltrate your wallet seed. It should also go without saying that you should generate your own BIP39 seed, and do not just use the example one that is shown by default to everybody.