what does to be hoisted by one's own petard?
A petard was a medevil era explosive device placed against the door or wall of a castle. There was a fuse. A person lit the fuse. Often the fuse malfunctioned and caused a premature explosion. Yes the door got blown down but the poor SOB lighting the fuse aldo got blown to bits. So in current terms you become a victum of your own actions. Eric
