A Grim Reaper is the kinky fore-play act of a man doing a handstand, while the female grabs his scrotum, and then pulls it up and over his asshole. Called a Grim Reaper because of the immense pain it causes to the receiving party, while also making a Scythe like motion of the scrotum.
Also called "Getting Grim" or just "The Reaper" for short.
Ed- "Hey Ben, I really want to try something funky and new out with Cassady, should I let her give me the Grim Reaper?"
Ben- "Don't fear the Reaper"