The best way to get the right answer on the internet is to post the wrong answer.
Cunningham’s law is named after Ward Cunningham, the inventor of wiki software. According to the law’s author, Steven McGeady, Wikipedia may be the most well-known demonstration of this law.
Cunningham’s Law can be considered the Internet equivalent of the French saying “prêcher le faux pour savoir le vrai” (“preach the falsehood to know the truth”). Sherlock Holmes has been known to use the principle at times (for example, in The Sign of the Four). In “Duty Calls” (“Someone is wrong on the Internet”), xkcd references a similar concept. The Chinese idiom 拋磚引玉 “tossing a brick to attract jade” expresses a similar concept, though that idiom can refer to proposing something imperfect or of lower quality, but not necessarily false or wrong.