As part of my volunteer work at a local research library, I work with newspapers from the late twentieth century.  In a paper from 1978, I found an article describing three-legged pantyhose, with a picture similar to this:

The idea is that when you get a run in one leg, you can put on the spare leg, thus making your pantyhose last longer.  My only question is, what do you do with the spare leg before you need it?