Ferret Wrenching occurs when you gape open the rectum of a ferret, and proceed to go balls deep. Now that the ferret is snugly wrapped around your Johnson you take their arms and make it cosplay as a machine gun but......instead of bullets, you guessed it! Your hot gooey semen. As you nut, filling the ferret with love the teeth act as a bullet carver, giving you spurts of semen the perfect shape.
To have a guy bend over with his ass in the air and have another guy side straddle the other guy and push his scrotum in his rectum. The following looks like a wrench and creates torque on the bottom guy's rectum.