I get that it’s just slang to describe a shirt but my lady was abused and beaten repeatedly by her husband so it’s a little personal. When we met in Texas she didn’t trust guys to treat her right.I never thought about it. It just seems like the easiest way to describe them. When you say it, people know what you're talking about.
On a related note, it used to be a thing among, eh, enlightened folk, to comment in an argument something like " When did you stop beating your wife?" To which I replied " When your wife started letting me beat her."
I have to say for an old man I’m one lucky guy. Not only very beautiful but also very intelligent.