The pattern link is to the original worsted weight version of the sock. These are socks knitted from the toe up, with a standard turned heel (worked backwards). The pattern began as an April Fool’s Day joke – the joke being that when finished, they look exactly like the very plainest of socks. The name comes from this joke, plus the fact that you can try them on as you go to check the fit of the foot.

The website also has a chart for converting this basic pattern to any combination of yarn size and foot size.