Now, we know what you’re thinking, but no, these are neither socks nor leg-warmers: they are, in fact, "Boot Sleeves", and as the name suggests, they’re basically "sleeves" that you pull on over your shoes in order to instantly transform them into "boots".
The problem with this, of course, is that as far as we can see, the "Boot Sleeves" do nothing of the sort, and instead, make your shoes look like… shoes worn with a sleeve over the top of them. Oh well. If that just so happens to be the look you’re after, you can buy them here.
(Thanks to Kelsey for the report!)