Th phrase comes down to us from the medieval fortress/castle siege-forces explosive weapon, the petard, which was deployed by one person while sheltered from tower/wall defensive action, in a small portable shed moved up to a castle door--upon which the soldier would nail the petard [to the door]---then, if all went smoothly, he would be removed via the shed [or running by foot!].
If the explosive fuse-time was too brief, the attacking person was "hoist on his own petard."

I think the modern American definition in the back room dictionary is to "shit or get off the pot".