Sarcasm, irony, and satire are figures of speech involving statements that are untrue in a literal sense. However, it is expected the audience should understand that the remarks are not true, and will consider them insulting or humorous.
The gullibility of conspiracy theorists is a popular subject of sarcasm, irony, and satire. But being so gullible means many of them are unaware that the remarks are not really true. Many of these people wrongly consider the sarcastic, ironic, and satirical messages as true, and the messages spread as hoaxes in their community.