Re: Judas Priest
I've heard some old-timers use it occasionally. It's a substitution for "Jesus Christ" used as an expletive, much as the expressions "chickendirt" and "son-of-a-gun" arose as marginally polite stand-ins for the more R-rated equivalents. Also the name of a 1970s and '80s heavy-metal band, the grooves of whose albums I wore out as a lad.
I don't recommend "Judas Priest" as even a substitutionary expletive: a second-order version of using our Lord's name in vain is too close to the real thing for my taste. Also, see the reference to "old-timers" above: if there's anything worse than risking blasphemy, it's risking being a blasphemous fogey.