The act of bending your girlfriend over in front of a woodchipper, with her head inside the opening, not all the way though, while having anal sex with her. Then have a fan blow her long hair in to the woodchipper, so it catches on to the gears and starts ripping her scalp off and the woodchipper blades slowly but surely start chipping away at the layers of her newly exposed skull bone.
Sometimes you can pull her out and smash her exposed skull in with a hammer and skullfuck her so your dick keeps thrusting in to her brain.
boyfriend: wanna get woodchipped?!
girlfriend: fuck yeah!
*boyfriend performs the woodwchipped*
Boyfriend: HAHAHA! I'm fucking a bonehead