Welcome to the forum - and you are certainly not an idiot! "Living proof" = an excellent example of something
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CliveHi guys,
More specifically, I see living proof as referring to a living creature, usually a human being, whose existence is being argued as proof of something.
eg Mary is 100 years old. She has smoked a pack of cigarettes a day for sixty years. She ids living proof that smoking is good for one's health.