Trump was photographed this week with red splotches on his hand, which kicked off a round of wild speculation on social media.
Kimmel said people are pointing out online that it’s “a common symptom of syphilis.”
Kimmel noted that Trump once said avoiding STDs was his “personal Vietnam.”
“But if he has syphilis, that would mean the only Vietnam he avoided was Vietnam,” he added.
Kimmel then played a video matching the known symptoms of syphilis to videos of Trump’s behavior over the years.
Kimmel isn’t really buying the syphilis theory.
“It’s probably ketchup,” Kimmel guessed. “He probably got his hands in a container of curly fries or something.”
But he said the former president would handle this a lot differently if one of his rivals were photographed with a splotchy red hand.
“He’d be all over it. He’d talk about it for years. He’d be posting in all-caps about ‘Meatball Ron DeSyphilis’ and ‘Nikki Herpes,’” Kimmel said. “But they haven’t brought it up.”
See more in his Thursday night monologue: