why does your tongue get stuck to iron/steel in freezing weather, but not other body part?
Totally uneducated response, but I would assume it’s due to the moisture content on the surface of your tongue. I think it’s actually the moisture freezing between your tongue and the iron/steel/really cold conductive thing that acts as a bridge or adhesive between the two mediums. If you got your hand nice and wet then put it on a freezing-temperature metal object, you’d likely see the same thing happen. Basically, it’s less a matter of your tongue getting stuck to “the thing” and more your tongue getting stuck to the frozen saliva, which itself is also stuck to “the thing.”
ELI5: Tongue = wet…. Other body parts in winter: Usually dry. The water will freeze instantly when it touches an extremely cold piece of metal. However, the same is true if your fingers were wet.
Try it sometime, get your hand wet and grab a piece of ice. The ice has to be relatively dry though (as in not melted yet, I’m not talking about “Dry Ice” as in solid CO2)
Because your tongue usually has moisture on it that will freeze on contact with the metal which is below freezing point. If you had damp hands they’d probably freeze to the metal as well.