But I got it from a definition I seen.. Something to do with:
"deathly ghost", "ghost", "ghostly shadows".
I tried to get you some links but I can't seem to find them anymore....
Kind of self explanatory, However it derived years ago when I began training in the Martial Arts. Many times I would show up at the studio and the guys would come out with "The American Sensei has arrived" in a goofy tone.