polystyrene ankle protectors

here are two polysteyrene packaging things which have holes just wide enough to put your feet in (as demonstrated by my leg here).
i was going to put them on and walk the rest of the way to work, but decided not to when i’d got the first one on. there was a real danger of street fallage.
And jane would skin-me-alive if i went through the knees of my work trousers.