In 1938, MGM movie Tarzan Johnny Weissmuller picked him out of 300 hopefuls to play his adopted son, Tarzan Jr., renamed Boy, in Tarzan Finds a Son! He kept the role going for eight movies at MGM and RKO.
As the years passed, Boy co-opted Jane's role as Damsel in Distress: in the climactic scene of every movie, he was tied to something and about to be killed or violated while Tarzan rushed to the rescue. Tarzan and Boy became the chief jungle couple, while Jane took to staying home in the Escarpment, or leaving altogether ("visiting America").
Big John and Little John were inseparable off-camera, too. Weissmuller was married to Beryl Scott at the time and having innumerable affairs with men and women, but it was Johnny Sheffield who appeared with him at the Brown Derby and the Trocadero, at movie premieres, on drives up the coast to Malibu. When Johnny was fifteen, Weissmuller bought them a house on the beach near Santa Barbara, where they could get away for weekends of swimming, fishing, and sunbathing, just the two of them.
In the 1940s, no tongues wagged about the "couple." Many people were not aware that LGBT people existed, and those who did thought only of swishy queens. Johnny Weissmuller was 6'4" and all muscle, a "real he-man." No way he could be a "swish."
And, in fact, there was nothing sexual going on: Weissmuller never touched Johnny in that way. Even as a teenager, when he developed a beautifully muscled physique and a dazzling matinee idol smile.
Even when the Tarzan series ended and they separated, Big John to play Jungle Jim (1948-1955) and Johnny to star in his own Bomba the Jungle Boy series (1949-1955), Big John still treated him as a little brother, a son.
Johnny found this odd -- since around his 15th birthday, every single person he met, man or woman, boy or girl, without exception, wanted to peek under his loincloth. And he gave quite a few of them the opportunity: Tommy Cook, his costar in Tarzan and the Leopard Woman; Peggy Ann Garner, his costar in Bomba the Jungle Boy; Cesar Romero, Bobby Driscoll, Jean Simmons. Why was Weissmuller immune to his trademark flirting?
He was especially interested because he had heard from several of Big John's former lovers that he was gifted with the biggest penis in Hollywood, a veritable third leg. Johnny was always a bit self-conscious about his size, and anxious to see what a Greek god looked like.
One day in the summer of 1953, they went swimming, and Big John, as usual, carefully turned his back to put on his swimsuit. Johnny had had enough. "Why don't you ever show me your manhood?" he asked. "You'll show any stranger on the street. You're more proud of it than your Olympic medals. Aren't I important enough to rate?"
Johnny chuckled. "I promise I won't go to bed with you. Lord knows I get enough offers as it is."
Big John still refused, but Johnny persisted, and cajoled, and flashed his trademark flirting smile, and finally he said "You're a little pain in the neck, you know that? One look, fine, but no touching."
The rest of the story, with nude photos and explicit sexual situations, is on Tales of West Hollywood.