Anal rail gun

The act of suppositing a large, mortar shaped metal butt plug into the anus, then nipping down to your local hospital for your MRI scan.
The magnetic resonance has been known to instantly accelerate the supposited metal object up to the speed of sound and deposit it elsewhere in the torso.

"Hey Arthur, did your wifes hospital appointment get in the way of your sexy weekend away?"
"On the contrary Jim, we were banging like the shit house door when the plagues in town. Hospital appointment looming and with her voyeuristic ambition, things got really sexy and I coaxed her into an anal rail gun.