"Bubba Ho-Tep".
Elvis is alive an well, well alive anyway and is a resident of a care home in Mud Creek, Texas. This is a result of him getting bored with life and swapping places with Elvis impersonator Sebastian Haff, who kicked the bucket before they could swap back. Also resident is President John Fitzgerald Kennedy who, after the Dallas assasination attempt, was patched up, dyed black to disguise him and dumped out of the way.
Anyhoo, the care home is being stalked by an evil mummy, the eponimous Bubba Ho-Tep, dressed in a stetson and cowboy boots. Bubba was on loan from Egypt touring the museums of the good ole US of A when he was stolen for ransom. The thieves took him in a bus which they crashed into the river near the home. Bubba survives by sucking the souls of the elderly.
Elvis and JFK resolve the save the world. The rest, as they say, is history.
Uh huh, Thank you very much.
So bad that I loved every minute of it