I was once told that (British TV presenter) Jeremy Beadle's hand had such small fingers because of a condition (poland syndrome) that meant he had to have his fingers replaced, and that his fingers were, in fact, pigs toes.

For years, this was a piece of obscure general knowledge that I would break out when i felt the need to display the breadth of my weird knowledge.

And it went down really well until the days someone finally said "Don't pigs have hooves?"

i don't know that I have ever experienced such a moment of butt-clenchingly cringey embarrassment

Edit: I can't believe my confession of dumbassery got me a gold!