Plow Pose
How: Lie on back with knees bent and pulled in near chest. Straighten legs so they're perpendicular to the bed. Brace lower back with hands and bend at the hips to lower legs overhead, feet together. Partner can kneel behind or stand if you're near the edge of the bed.
Why: "It allows for deep penetration," Herbenick says. (So it might not be your best choice if you find cervical contact uncomfortable or have an unusually well-endowed partner.)