What's a phrase you misinterpreted the meaning of for the longest time?

I thought kid gloves were for dealing with kids but actually they’re made from the skin of kids.

Also of note, I thought the kids were children.

I’ve seen people using “that’s what she said” in a very serious setting, as a way to say “good point/touché”.

As in there was a literal she who literally said that? Otherwise I can’t understand this.