When John was growing up, his mom died. This is referenced in the Beatles song Julia, off of the album The Beatles. It is also referenced in Mother, off of Plastic Ono Band. It is again referenced in My Mummy's Dead, also off of Plastic Ono Band.
See Also: The Beatles
After The Beatles broke up, John decided he should probably do something and released some avant-garde albums, because Revolution 9 was that good. Then he released Plastic Ono Band, which was great and then he released Imagine which was great and then nothing important happened. Then he died.
In 1980, Mark David Chapman decided he wasn't crazy enough and chose to go shoot John Lennon. This is due to him being a part of an ancient Octopus cult that wanted to end the Theodore Roosevelt dynasty so they could take over the world. So he shot John Lennon and Johnny died.
John Lennon, as a Son of Theodore Roosevelt, fathered many children. Among them are Julian Lennon, Jenna Rose, Melon, Kid Flash, Mount Roosevelt sculptor Gutzon Borglum, Pharaoh Seti I, Katy Perry, Chuck Mangione, The Somali Civil War, Japanese Impressionist Miracle Hikaru, Canadian Sexologist Robin Milhausen, American Football Player Buck Flowers, Vladimir Lennon and also some hipster named Sean.
John Lennon was a nudist. You can tell because the cover of Two Virgins features him naked.
Brian Epstein was The Beatles' manager. Even though the public didn't know until after he died, it was an open secret to his business associates and friends (including Lennon and The Beatles) that he was gay. John often joked about this, such as pointing to every male they came across and asking him if he liked them. Clearly they were joking around about their secret affair.
Don't believe me? Biographer Phillip Norman claims that the main reason Epstein agreed to manage The Beatles (who, at that point, had been turned down by basically every record label in England) was because he was physically attracted to John. Furthermore, just after John's wife 'gave birth' to his first son, Julian, John decided to go on vacation in Spain. With Epstein. Tabloids, naturally, ate this up, calling them in love.
John, however, wasn't a one-man man. In the movie A Hard Day's Night (which is on instant on netflix) John attempts to kiss a man. Later on, the fake manager in the movie informs John that he must do something, threatening that he would tell the public John's "secret" which is probably homosexuality.