There is an informal “Small Penis” rule, which authors use to protect themselves against libel lawsuits, by saying that a character they based off of someone else has a small penis, which stops most people from wanting to associate themselves with that character by suing the author

The “small penis rule” is an informal strategy used by authors to evade libel lawsuits. It was described in a New York Times article in 1998:

“…For a fictional portrait to be actionable, it must be so accurate that a reader of the book would have no problem linking the two,” said Mr. Friedman. Thus, he continued, libel lawyers have what is known as ‘the small penis rule.’ One way authors can protect themselves from libel suits is to say that a character has a small penis, Mr. Friedman said. “Now no male is going to come forward and say, ‘That character with a very small penis, that’s me!’ “

The small penis rule was referenced in a 2006 dispute between Michael Crowley and Michael Crichton. Crowley alleged that after he wrote an unflattering review of Crichton’s novel State of Fear, Crichton libeled him by including a character named “Mick Crowley” in the novel Next. In the novel, Mick Crowley is a child rapist, described as being a Washington-based journalist and Yale graduate with a small penis.