The tweet is in response to a preliminary paper [1] [2] studying text found in images generated by, e.g., "Two whales talking about food, with
subtitles." DALL-E doesn't generate meaningful text strings in the images, but if you feed the gibberish text it produces -- "Wa ch zod ahaakes rea." back into the system as a prompt, you would get semantically meaningful images, e.g., pictures of fish and shrimp.
[1] https://giannisdaras.github.io/publications/Discovering_the_...
[2] https://twitter.com/giannis_daras/status/1531693093040230402