Untreatable.com
Fake medical diagnoses for problems you definitely do not have.
Untreatable.com issues diagnostic reports for conditions that do not exist. The comedy is entirely in the register — it plays the whole thing straight, in the flat clinical language of an actual medical write-up, and never once winks at you.
It is a one-joke site, but it is a well-built one joke. The deadpan holds all the way through the report, which is the only way this format works.