I don't know what it is with mummies this Halloween, but in addition to the terrifying Life-sized Wrapped Mummy Statues, I think this realistic full-color translucent poly-film Menacing Mummy Window Poster certainly adds to the effect. Simply trim this scary poster to fit your window and let trick-or-treaters and your neighbors, during the rest of the month, think you are harboring an undead ancient monster in your living room or upstairs bedroom. It'll definitely make people take a second glance as their hearts skip a beat. It's a subtle, but effective effect.
P.S. Trim it to fit on your friend's passenger side car window for some more laughs.