Prison pants when equipped spawns a pair of Military boots at your feet, even when wearing some boots and when not wearing boots.
As seen on these 2 pictures that I don't have any boots on me and they appear, they are visual for other players as well when running around the map.

https://i.gyazo.com/c0cb4b5eeb8f4b562cedcfc41411f9b8.jpg
https://i.gyazo.com/cb0cbacf5e2dd72547bb1f8707a35121.jpg