I actually did it. This was back in the times when you could get a job the next day, and my new employer didn't want me keeping anything from the old employer by the time I started. Old employer was dragging their feet on the shipping label and made it clear that failure to return the equipment would be considered theft. I gave them a week of daily reminder emails with an approaching deadline (no response), then handed it to the cops as abandoned property. Got a few HR calls immediately afterwards asking how to pick it up, and an annoyed police call asking me not to do it again.