Haha! yay someone else who knows about party lines, I guess we're revealing our ages aren't we? That was ancient technology. I hadn't heard that called "rubbering" but yes it was the specialty of all the old ladies in the neighborhood!
It was a bit of a hassle because they'd be on the phone for hours and finally you'd have to break in and ask them to hang up so you could make a call, and then they'd get back on and listen in! lol.