Lennin had a friend named Phil and he stopped aging as a teenager. Because of his looks, people kept on insisting he was a teenager, even if they knew better. Lennin got really mad at all of the people that knew better but liked to pretend Phil was a teenager and coined the word Phil-is-teen. He expanded this usage to anyone that spoke falsehoods often that were known to be false.

source: Black Book Of Communism page “Trust me bro”