If you're hiring people who are engaged and genuinely interested in what they're doing and giving them a reasonable workload(!), they're likely to just treat that day as a day they can work from home with the option to not do work if life suddenly has plans for them.
XKCD-style admins, for instance, are likely to just spend that day spitballing ways to reduce downtime (which make the other 32 hours less annoying) and hardening infrastructure without having to worry about producing results. Planning is everything for that sort of work. My occasional work-from-home days were frequently days when I'd get a positively lurid number of things done just because of fewer interruptions.