John doo doo head (or John Gayham) is a bad guy villain who appears in two of SMG4's bloopers, his main appearance is in the episode Desert Head, which he antagonized.
Ever since John Gayham was "a little girl" he had nowhere to live, then one day he came across the pyramid and loved it like a woman. He claimed that anyone who entered it was doomed and would trick them to play pyramid puzzles and made them die with the help of his henchmen. At the end of Desert Head, he was crushed by SMG4 and X riding a helicopter. He later was revived along with a lot of other bad guys in Smg3's plan to destroy Smg4 cause he felt like it, and later appeared in The Wacky Wario Bros.: Money Mayhem in where he robbed a bank with a Goomba, but their money was stolen by Wario and Waluigi who was hiding in the truck's cargo.
In Desert Head, his last name was spelled "Gayham", however in Smg3's plan to destroy Smg4 because he felt like it, it's re-spelled to "Geyham".
John Gayham is one of the three minor characters to reappear in a recent Blooper after a long absence, the other ones being Crazy Toilet Dude and The Visitor (Gayham and The Crazy Toilet Dude didn't appear for one and a half year, while The Visitor was away for three years).