Heard of this?
I've never rested my barrel on my boot nor known anyone who does but I guess it must be a common practice. Orvis markets this product for doing so.

https://www.orvis.com/p/magnetic-to...jjsxvZMM6IT2lg_ydJ_8ExIXz9A72ouL25-WjzpA

Some do it while shooting trap, skeet, clays etc.

I always thought it was stupid, but better your toes than my head.

Trap and skeet shooters use it while they are waiting for their turn to shoot....Shotguns..over/under or SxS... are unloaded or sometimes loaded and open until the time the barrel is taken off the pad to shoot...Been in use for decades....

I guess sometime someone took off a toe.....but it would have been extremely rare......in that the rules are you don't close the gun until it is your turn to shoot....

I would be more concerned about those who lean a loaded gun against the car....or lay a loaded gun on the tailgate.....