My husband and I don’t fight very often, but one thing we do fight about is how he calls aluminum foil "tin foil" and he's like "IT'S THE SAME THING!" and I’m like "bruh, they are completely different metals, so please go consult the periodic table I've hung above our bed."
@Alice Let it go. It's an idiomatic expression.
@erinoriordan I think you meant idiotic expression.
@Alice It can be both.