"[When someone tells a joke] Simon is there, literally snotting into his hand," Holden revealed on UK TV show This Morning.
"Liquid comes out of his face when he is really laughing. He pinches his nose to stop himself."
The embarrassing condition is so bad that Simon has developed a technique to avoid any mucussy mishaps when he's on TV.
"You know everyone has a showbiz laugh and then everyone's got a real laugh?" says Holden. "He's got a real laugh that he has to pinch his nose for, otherwise snot comes out!"
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